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Comparative morphology of two closely related species of the Cottid genus Myoxocephalus Cowan, Garry I. McT. 1965

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COMPARATIVE MORPHOLOGY OF TWO CLOSELY RELATED SPECIES OF THE COTTID GENUS MYOXOCEPHALUS by GARRY I. MCT. COWAN B.Sc.(Hons), University of B r i t i s h Columbia, 1963 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Zoology We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1965 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r -m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e H e a d o f my D e p a r t m e n t o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i -c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t b e a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r 8 , C a n a d a D a t e V 2 ^ . k ^ i ABSTRACT A d e t a i l e d m o r p h o l o g i c a l study has been made between two a p p a r e n t l y c l o s e l y r e l a t e d s p e c i e s of the c o t t i d genus Myoxocephalus ( S t e l l e r ) T i l e s i u s , Myoxocephalus polyacanthocephalus P a l l a s and Myoxocephalus iaok (Cuvier and V a l e n c i e n n e s ) , Large s e r i e s o f both s p e c i e s were examined. C o l o r a t i o n was found to be one of the major d i f f e r e n c e s , between the two s p e c i e s . They were a l s o found to d i f f e r i n the degree of sexual dimorphism. Sguamation, the l a t e r a l l i n e system, and o s t e o l o g y were examined by c l e a r i n g and s t a i n i n g . The s c a l e s and l a t e r a l l i n e o s s i c l e s were found to be m o r p h o l o g i c a l l y d i s t i n c t . The o s t e o l o g y was e s s e n t i a l l y s i m i l a r i n both s p e c i e s , the o n l y major d i f f e r e n c e b e i n g the l o s s of the t h i r d p r e o p e r c u l a r spine i n M„ iaok. The musculature of head and caudal r e g i o n s was examined i n d e t a i l b u t no s i g n i f i c a n t d i f f e r e n c e s were encountered. A p r e l i m i n a r y examination of the 1 muscle p r o t e i n s by means of s t a r c h - g e l e l e c t r o p h o r e s i s was a l s o undertaken. D i s t i n c t d i f f e r e n c e s i n the m o b i l i t i e s of s e v e r a l p r o t e i n bands were encountered. Analyses of m e r i s t i c c h a r a c t e r s r e v e a l e d l a r g e v a r i a t i o n , and almost complete range o v e r l a p between the two s p e c i e s . The modes of s e v e r a l of these counts however, were d i f f e r e n t . Morphometric c h a r a c t e r s i n d i c a t e d c l o s e s i m i l a r i t y and of the 32 measurements taken and the 992 combinations compared, o n l y two y i e l d e d s i g n i f i c a n t differences„ These were depth of caudal peduncle a g a i n s t l e n g t h of a n a l f i n i i base and depth of caudal peduncle a g a i n s t length of second d o r s a l f i n base. i i i TABLE OF CONTENTS PAGE ABSTRACT i TABLE OF CONTENTS i i i LIST OF TABLES v i LIST OF FIGURES v i i ACKNOWLEDGEMENTS X INTRODUCTION 1 MATERIALS AND METHODS 3 C o l l e c t i o n of M a t e r i a l 3 M a t e r i a l s Examined - Myoxocephalus polyacanthocephalus 3 M a t e r i a l s Examined - Myoxocephalus iaok 11 Method o f Measurement 13 D e f i n i t i o n of Measurements 13 M e r i s t i c C haracters 17 C l e a r i n g and S t a i n i n g Technique 18 O s t e o l o g i c a l P r e p a r a t i o n 19 X-ray Technique 19 E l e c t r o p h o r e t i c Technique 20 S t a t i s t i c a l Technique 21 RESULTS 23 C o l o r a t i o n o f M„ polyacanthocephalus 23 Comparison of C o l o r a t i o n o f M„ polyacanthocephalus and M. iaok 26 Sexual Dimorphism i n C o l o r a t i o n o f M„ polyacanthocephalus 29 Comparison of Sexual Dimorphism i n C o l o r a t i o n o f M„ polyacanthocephalus and M. iaok 29 The C e p h a l i c L a t e r a l Line System of M„ polyacanthocephalus 30 The L a t e r a l Line System o f the Body o f M'„ polyacanthocephalus 33 The L a t e r a l L i n e O s s i c l e s o f M. polyacanthocephalus 35 Comparison of the L a t e r a l L i n e O s s i c l e s o f M„ polyacanthocephalus and M„ iaok 36 i v The Squamation o f M 0 polyacanthocephalus 40 Comparison of Squamation o f M„ polyacanthocephalus and M. iaok 40 The P e c t o r a l F i n P a p i l l a e o f M„ polyacanthocephalus 46 Comparison o f P e c t o r a l F i n P a p i l l a e o f M. polyacanthocephalus and M„ iaok 46 The P e l v i c F i n P a p i l l a e o f M„ polyacanthocephalus 47 Comparison o f the P e l v i c P a p i l l a e o f M. polyacanthocephalus and M. iaok 49 Spines and C r e s t s on the Head o f M„ polyacanthocephalus 51 a„ Spines o f the Opercular Apparatus 51 b„ Spines and C r e s t s o f the Top o f the Head 52 Comparison o f the Spines and C r e s t s of the Head o f M„ polyacanthocephalus and M„ iaok 53 a. Spines o f the Opercular Apparatus 53 bV Spines and C r e s t s of the Top o f the Head 54 The Muscles o f the Cheek Region o f M 0 polyacanthocephalus 54 Muscles o f the Opercular Apparatus of M„ polyacanthocephalus 57 Comparison of Muscles of the Opercular Apparatus of M. polyacanthocephalus and M, iaok 58 Muscles of the V e n t r a l Surface o f the Head o f M. polyacanthocephalus 62 Caudal Anatomy 63 Caudal S k e l e t o n o f M. polyacanthocephalus 65 Comparison o f the Caudal S k e l e t o n o f M 0 polyacanthocephalus and M. j.aok 67 The Muscles o f the Caudal F i n o f M„ po1vac anthoce phalu s 68 S u p e r f i c i a l Caudal Musculature 68 S u p e r f i c i a l D o r s a l F l e x o r Muscle 68 S u p e r f i c i a l V e n t r a l F l e x o r Muscle 68 Deep Caudal Musculature 69 Hypochordal L o n g i t u d i n a l Muscle 69 Deep D o r s a l F l e x o r Muscle 69 Profundal Caudal Musculature 71 I n t e r r a d i a l Muscles 71 Comparison o f Caudal Muscualture o f M„ polyacanthocephalus and M„ iaok 75 S t r u c t u r e o f B r a n c h i a l Apparatus o f M. polyacanthocephalus 75 Comparison o f the B r a n c h i a l Apparatus o f M„ polyacanthocephalus and M„ iaok 76 V The M o r p h o l o g y o f t h e O l f a c t o r y R o s e t t e o f "M. p o l y a c a n t h o c e p h a l u s 76 C o m p a r i s o n o f t h e M o r p h o l o g y o f t h e O l f a c t o r y R o s e t t e s o f M. p o l y a c a n t h o c e p h a l u s a n d M„ iaok 78 E l e c t r o p h o r e s i s o f M u s c l e P r o t e i n 78 C o m p a r i s o n o f M e r i s t i c C h a r a c t e r s o f M„ p o l y a c a n t h o c e p h a l u s a n d M„ iaok 82 C o m p a r i s o n o f M o r p h o m e t r i c a n d Age R e l a t e d Measurements o f M. p o l y a c a n t h o c e p h a l u s a n d M„ iaok 89 E c o l o g y a n d L i f e H i s t o r y o f M. p o l y a c a n t h o c e p h a l u s 91 E c o l o g y a n d L i f e H i s t o r y o f M„ iaok 91 G e o g r a p h i c D i s t r i b u t i o n o f M 0 p o l y a c a n t h o c e p h a l u s 92 G e o g r a p h i c D i s t r i b u t i o n o f M„ iaok 92 D e p t h D i s t r i b u t i o n o f M. p o l y a c a n t h o c e p h a l u s 93 D e p t h D i s t r i b u t i o n o f M„ iaok 93 DISCUSSION 94 SUMMARY 104 LITERATURE CITED 109 v i LIST OF TABLES PAGE Table I . M e r i s t i c Comparison o f M. polyacanthocephalus and M. i aok .• 85 v i i LIST OF FIGURES F i g u r e 1. F i g u r e 2 F i g u r e 3. F i g u r e 4» F i g u r e 5. F i g u r e 6. F i g u r e 7„ F i g u r e 8„ F i g u r e 9„ F i g u r e 10. Figure.11„ F i g u r e 12. F i g u r e 13. F i g u r e 14„ F i g u r e 15„ F i g u r e 16. PAGE Major : C e p h a l i c L a t e r a l L i n e Canals o f M, polyacanthocephalus„ 34 Pore P a t t e r n o f C e p h a l i c L a t e r a l L i n e System of M„ polyacanthocephalus«, 34 L a t e r a l L i n e O s s i c l e of M. polyacanthocephalus„ 38 The R e l a t i o n s h i p Between L a t e r a l L i n e O s s i c l e s i n M. polyacanthocephalus «, 38 L a t e r a l L i n e O s s i c l e o f M. iaok. 39 Scale Types found i n M. polyacanthocephalus. 43 Scales o f M, polyacanthocephalus i n s i t u . 43 Scales From the Region Above the L a t e r a l L i n e of M. i a o k . a. s t e l l a t e t u b e r c l e from a n t e r i o r end; b. from middle; c„ from p o s t e r i o r end. 44 Types of Scales Found Below the L a t e r a l L i n e i n M. . iaok.• 45 P e c t o r a l P a p i l l a e o f A d u l t Male M. polyacanthocephalus. 48 P e c t o r a l P a p i l l a e o f A d u l t Male M„ i a o k . 48 P e l v i c P a p i l l a e o f A d u l t Male M 0 polyacanthocephalus. 50 P e l v i c P a p i l l a e o f A d u l t Male M a iaok,, 50 S u p e r f i c i a l Muscles o f the Cheek Region o f M. polyacanthocephalus. 59 S u p e r f i c i a l Muscles o f the Cheek Region o f M„ polyacanthocephalus w i t h S u b o r b i t a l S e r i e s Removed. 59 Deep Muscles of the Cheek Region o f M„ polyacanthocephalus. 60 v i i i F i g u r e 17. F i g u r e 18. F i g u r e 19. F i g u r e 20, F i g u r e 21. F i g u r e 22„ F i g u r e 23. F i g u r e 24. F i g u r e 25. F i g u r e 2 6. F i g u r e 2 7. F i g u r e 28. F i g u r e 29. F i g u r e 30„ F i g u r e 31. Deep Muscles o f the Cheek Region o f M, polyacanthocephalus ( S u p e r f i c i a l S l i p s o f Adductor M a n d i b u l i Removed), 60 Muscles of the Cheek Region o f M, polyacanthocephalus (Adductor M a n d i b u l i Complex and Levator Arcus P a l a t i n i Removed), 61 Muscles o f the Opercular Apparatus of M„ polyacanthocephalus (Operculum Removed)„ 61 S u p e r f i c i a l Muscles o f the V e n t r a l Surface o f the Head o f M. polyacanthocephalus, 64 Deep Muscles o f the V e n t r a l Surface o f the Head o f M. polyacanthocephalus , 64 The Caudal Skeleton o f M. polyacanthocephalus. 72 The P o s t i o n o f the Hypochordal L o n g i t u d i n a l Muscle o f M„ polyacanthocephalus. 72 The Deep Caudal Musculature o f M, polyacanthocephalus. 73 The Deep Caudal Musculature o f M. polyacanthocephalus Showing S u p e r f i c i a l Bundle o f Deep V e n t r a l F l e x o r , 73 The S u p e r f i c i a l Caudal Musculature o f M, polyacanthocephalus. 74 The B r a n c h i a l Apparatus o f M„ polyacanthocephalus, 77 The O l f a c t o r y Rosette o f M. polyacanthoce-phalus. 79 The O l f a c t o r y Rosette of M, iaok, 79 S t a r c h - g e l Electropherograms o f the Muscle P r o t e i n s o f ; A. M„ polyacanthocephalus and M. iaok, 81 Comparison o f V a r i a t i o n i n Spine Number o f F i r s t D o r s a l F i n i n M. polyacanthocephalus and M. iaok, 86 i x F i g u r e 32, F i g u r e 33, F i g u r e 34, F i g u r e 35. F i g u r e 36„ F i g u r e 37, Fi g u r e 38, Fi g u r e 39, F i g u r e 40; Fi g u r e 41, Fi g u r e 42, F i g u r e 43 Comparison o f V a r i a t i o n i n Number o f Rays and D o r s a l F i n i n M„ polyacanthocephalus and M. iaok. 86 Comparison of V a r i a t i o n i n Number o f A n a l F i n Rays i n M„ polyacanthocephalus and M. iaok„ ; ' • 86 Comparison o f V a r i a t i o n i n V e r t e b r a l Number i n M. polyacanthocephalus and M, iaok. 86 Comparison of V a r i a t i o n i n L a t e r a l L i n e Pore Number i n M,: polyacanthocephalus and M„ iaok. 87 Comparison o f V a r i a t i o n i n the Number of the Longest P e c t o r a l F i n Ray i n M„ polyacanthocephalus and M. i a o k 0 87 Comparison o f V a r i a t i o n i n the Number of the Longest P e l v i c F i n Ray i n M. polyacanthocephalus and M. jaok„ 87 Comparison of V a r i a t i o n i n the Number o f the Longest Caudal Ray i n M. polyacanthocephalus and M. iaok. 87 Comparison of V a r i a t i o n i n the Number of the Longest 1 s t D o r s a l Spine i n M„ polyacanthocephalus and M. iaok. 88 Comparison of V a r i a t i o n i n the Number o f the Longest 2nd D o r s a l Ray i n M„ polyacant?iocephalus and M„ j a o k 0 88 Comparison o f V a r i a t i o n i n the Number of the Longest A n a l Ray i n M„ polyacanthocephalus and M„ jaok. 88 Comparison o f the R e l a t i o n o f Depth at. Caudal Peduncle w i t h Length o f A n a l F i n Base i n M. polyacanthocephalus and.M. iaok„ 90 Comparison o f the R e l a t i o n o f Depth a t Caudal Peduncle w i t h Length o f Second D o r s a l F i n Base i n M„ polyacanthocephalus and M, jaok„ 90 ACKNOWLEDGEMENTS I wish to express my s i n c e r e g r a t i t u d e to Dr, N„ J , Wilimovsky, D i r e c t o r o f the I n s t i t u t e o f F i s h e r i e s , U n i v e r s i t y o f B r i t i s h Columbia, who suggested the problem and o f f e r e d much encouragement and ad v i c e throughout the course o f t h i s study, I would a l s o l i k e to thank Dr„ H. Tsuyuki o f the T e c h n o l o g i c a l S t a t i o n of the F i s h e r i e s Research Board of Canada, Vancouver, who made the E l e c t r o p h o r e t i c analyses o f the muscle samples, I am in d e b t e d to Mr, A, Gagne o f the U n i v e r s i t y o f B r i t i s h Columbia Computing Center who c o n s t r u c t e d the program f o r the s t a t i s t i c a l a n a l y s i s o f Morphometry, Drs,,: B, McK, Bary and.H, D„ F i s h e r o f the U n i v e r s i t y o f B r i t i s h Columbia who o p t i c a l l y r e a d the manuscript and o f f e r e d many h e l p f u l s u g g e s t i o n . T h e i r advice was g r e a t l y a p p r e c i a t e d . Thanks are due to the N a t i o n a l Research C o u n c i l o f Canada which f u r n i s h e d support f o r t h i s study. INTRODUCTION A t no time i n the h i s t o r y o f sy s t e m a t i c a has there been more d i s c u s s i o n about i t s : p h i l o s o p h i c a l b a s i s . S e i z i n g upon the o p p o r t u n i t y o f f e r e d f o r advanced treatments p r o v i d e d by d i g i t a l computers, an a c t i v e s c h o o l o f thought has been de v e l o p i n g the s o - c a l l e d system of numerical taxonomy. There are many v a r i a t i o n s i n d e t a i l s o f the phi l o s o p h y u n d e r l y i n g numerical taxonomy t h a t have been w e l l reviewed by Mayr (1965)„ One s c h o o l takes the p o s i t i o n that} a c l a s s i f i c a t i o n of l i v i n g organisms presents no e s s e n t i a l d i f f e r e n c e from a c l a s s i f i c a t i o n . o f inanimate o b j e c t s . Another s c h o o l r e p r e s e n t e d by Sokal and Sneath, w h i l e r e c o g n i z i n g t h a t there are e s s e n t i a l d i f f e r e n c e s between l i v i n g and n o n l i v i n g systems, o b j e c t s mainly to the sub-j e c t i v e p h y l o g e n e t i c i n t e r p r e t a t i o n f r e q u e n t l y i n d u l g e d i n by c l a s s i c a l Linnaean s y s t e m a t i s t s , Some indeed urge t h a t the e n t i r e system of nomenclature c u r r e n t l y used be abandoned i n favour of w h o l l y numerical d e s i g n a t i o n s . In t h i s way they hope to a v o i d i n f e r e n c e s o f r e l a t i o n s h i p which are i n h e r e n t i n the Linnaean system. No matter which p h i l o s o p h y i s favoured, a l l c l a s s i f c a t i o n s and subsequent i n t e r p r e t a t i o n r e s t s upon our c a p a c i t y to d e t e c t d i f f e r e n c e s between organisms. I t has been the custom to assume t h a t p e r s i s t a n t and wide-spread d i f f e r e n c e s are g e n e t i c i n t h e i r o r i g i n s . I t has been i m p l i e d t h a t the 2 g r e a t e r the number of d i f f e r e n c e s found the g r e a t e r the p o s s i b i l i t y of a r r i v i n g a t an a c c u r a t e i n d i c a t i o n of r e l a t i o n -s h i p and a t the o p p o s i t e end, the degree to which organisms are s p e c i a l i z e d and adapted to t h e i r environments. . In the p r e s e n t study I have undertaken a d e t a i l e d comparison of two s p e c i e s of c o t t i d f i s h e s c u r r e n t l y a s s i g n e d to the genus Myoxocephalus. Though the geographic ranges of these s p e c i e s are d i f f e r e n t i n t h e i r o u t e r boundaries, through most of t h e i r d i s t r i b u t i o n s they appear to occur s y m p a t r i c a l l y . No h y b r i d specimens have been found and i t can be assumed t h a t although a c l o s e r e l a t i o n s h i p may be i n f e r e d from t h e i r s i m i l a r i t i e s , there are e f f e c t i v e b a r r i e r s to t h e i r i n t e r b r e e d i n g . The t o o l s a v a i l a b l e to the student, of s y s t e m a t i c s have been g r e a t l y augmented d u r i n g the p a s t few y e a r s . B i o c h e m i c a l techniques such as those used i n immunological t e s t s , e l e c t r o p h o r e t i c examination of body p r o t e i n s , and more r e c e n t l y the matching of DNA permits the examination of deep seated d i f f e r e n c e s . A t the o t h e r extreme i t . has been shown t h a t behaviour i s an i n h e r i t e d c h a r a c t e r i s t i c of g r e a t importance to the s p e c i e s . Behaviour has a l s o been shown to be q u i t e d i f f e r e n t even i n c l o s e l y r e l a t e d s p e c i e s . T h i s study c o n s i s t s l a r g e l y of d e t a i l e d comparisons of anatomy and a p r e l i m i n a r y i n v e s t i g a t i o n i n t o the d i f f e r e n t muscle p r o t e i n s . I t i s hoped to o b t a i n an i n d i c a t i o n of some of those systems of l e s s g e n e t i c s t a b i l i t y which have p r i m a r i l y been concerned i n the e v o l u t i o n of t h i s group„ 3 MATERIALS AND METHODS C o l l e c t i o n o f M a t e r i a l The m a j o r i t y o f M. polyacanthocephalus and M, iaok were made a v a i l a b l e f o r examination by the I n s t i t u t e o f F i s h e r i e s , U n i v e r s i t y of B r i t i s h Columbia, Many c o l l e c t i o n s from the A l e u t i a n I s l a n d s which are i n the I n s t i t u t e o f F i s h e r i e s were taken by Dr, N, J , Wilimovsky and Mr, A. E, Peden d u r i n g the summers between 1961 and 1963, A d d i t i o n a l m a t e r i a l was c o l l e c t e d from the G u l f of A l a s k a by the I n t e r n a t i o n a l P a c i f i c H a l i b u t Commission. S e v e r a l specimens of M. iaok from the B e r i n g Sea were o b t a i n e d on l o a n from the C o l l e g e of F i s h e r i e s , U n i v e r s i t y of Washington. A d d i t i o n a l specimens of both s p e c i e s were observed a l i v e by the author w h i l e on a c o l l e c t i n g e x p e d i t i o n between C h e r i k o f I s l a n d and Unalaska I s l a n d on the Research V e s s e l G„ B, Reed i n August, 1964. These specimens have not y e t been c a t a l o g u e d and do not appear i n the s e c t i o n on M a t e r i a l s Examined, M a t e r i a l s Examined - Myoxocephalus polyacanthocephalus  Japan Rebun I s l a n d BC63-1087 Rebun I s l a n d BC63-1088 Okhotsk Sea 52 G20'N, 155°30'E. BC63-396 4 52°30'N. 155°10'E. BC63-402 U.S» S.R, 54°31 ,30' SN. 167°59 '30"E. 54°31 ,30"N. 167 o59 ,30"E. 1-1% f±. 1-1% f t . BC63-1042 BC63-1044 A l e u t i a n I s l a n d s and Al a s k a n P e n i n s u l a A t t U I s l a n d , e a s t o f Gasco P o i n t T i d e p o o l BC63 -880 AttU I s l a n d , e a s t o f Case© P o i n t T i d e p o o l BC63 -883 A t t U I s l a n d , near Murder P o i n t T i d e p o o l BC63 -885 A t t U I s l a n d , near Murder P o i n t T i d e p o o l BC63 -886 A t t U I s l a n d , NW shore of Massacre Bay T i d e p o o l BC63' -888 AttU I s l a n d , NW shore of A l e x i a l Cove T i d e p o o l BC63 -893 A t t U I s l a n d , base of Casco P o i n t T i d e p o o l BC63' -895 A t t U I s l a n d , Holekot Bay 0-8 f t . BC63' -904 A t t u I s l a n d , A l e x i a l P o i n t 0-4 f t . BC63 -1004 A t t u I s l a n d , N shore C h i c h i g o f Hbr„ 0-3 f t . BC63' -1006 A t t u I s l a n d , Massacre Bay 28 f t o BC63' -1009 A t t u I s l a n d , Massacre Bay, Navy Cove 20-30 f t . BC63' -1013 Shemya I s l a n d , SW shore T i d e p o o l BC63' -900 Kiska L I s l a n d , o f f wharf K i s k a Hbr. 0-35 f t . BC63--911 Amchitka I s l a n d , S t . Makarius P o i n t T i d e p o o l BC63' -303 Amchitka I s l a n d , Makarius Bay BC63' -1019 5 Amchitka I s l a n d , o f f o l d Loran S t a t i o n Amchitka I s l a n d , C y r i l Cove Amchitka I s l a n d , base o f K i r i l o f P o i n t Adak I s l a n d , N shore F i n g e r Bay Adak I s l a n d , N shore F i n g e r Bay Adak I s l a n d , Kuluk Bay W of Zeto P o i n t Adak I s l a n d , Zeto P o i n t S i t k i n I s l a n d , N o f S i t k i n Sand Bay I g i t k i n I s l a n d , o f f S s i d e Umnak I s l a n d , N i c k o l s k i Bay Umnak I s l a n d , on Kelp P o i n t Umnak I s l a n d , N i k o l s k i Bay Umnak I s l a n d , N i k o l s k i Bay Umnak I s l a n d , N i k o l s k i Bay Umnak I s l a n d , N of O t t e r P o i n t Unalaska I s l a n d Unalaska I s l a n d , Dutch Hbr. Unalaska I s l a n d , Dutch Hbr„ Unalaska I s l a n d , Dutch Hbr. o f f dock Caton I s l a n d 54°07'00"N o 164°58'18"W. 54 o05'50"N. 164°28'00 , ,W, 0-3 f t , 2 f t . T i d e p o o l 0-30 f t . 0-8 f t . 0-3 f t . 6-15 f t , 0-3 f t . 0-4 f t . 0-4 f t . 0-2 f t . 0-4 f t . 2 f t . 2 fath„ T i d e p o o l 1 f t . 47-48 f a t h , Izembek Bay BC63-1014 B C 6 3 - 1 0 1 8 B C 6 3 - 1 0 8 6 BC63-903 BC63-905 BC63-906 BC63-1150 BC63-1025 BC63-919 BC63-1068 BC63-1069 B C 6 3 - 1 0 7 0 B C 6 3 - 1 0 7 1 BC63-1073 BC63-1076 BC63-1335 BC63-1339 BC56-38 BC63-1375 BC63-1302 BC63-1311 BC62-502 BC63-1430 6 Izembek Bay, o p p o s i t e DEWline s i t e Izembek Bay, B l a i n e P o i n t Izembek Bay, o p p o s i t e DEWline s i t e C o l d Bay, o p p o s i t e Kelp P o i n t Caton I s l a n d Caton I s l a n d Caton I s l a n d , 54°24 I30"N. 162°28 ,24"W. 55 G13'30"N. 161°47 ,00"W. 54 o54'00"N. 161°0Q ,00 , ,W. 54°39'N. 160°45'W. 55°24 ,00 ! ,N. 160°33'00"W. 55°02'N. 160o18'40"W. 54°48'N„ 160o30'W. 54°15'40"N. 160°01'30"W. 55°33 ,30"N„ 159 o43»00"W. Shumigan I s . L i t t l e K o n i u j i I. Simeonof Island, near head of Hbr. Simeonof I s l a n d , near head of Hbr, Simeonof I s l a n d , near head of Hbr, 54°54'N, 158°30"W„ 55°36'G0"N. 158 o30'00"W. 55°42'N. 158°00'W, 56°31'N, 157°40'W. 56°48»N. 155°00'W. 0-1 m. 8 f t . 4-5 i n . T i d e p o o l T i d e p o o l 5 f t . 5 7-60 f a t h . 40 f a t h . 63 f a t h , 37-51 f a t h . 57 f a t h , 58 f a t h , i 247-250 f a t h , 51 f a t h . 0,5-1 f a t h . 4-10 f t , 4-10 f t , 2-4 f t . 105 f a t h . 75 f a t h . 68 f a t h . 55 f a t h , 54 f a t h . BC63-1433 BC63-1435 BC63-1439 BC63-1438 BC64-1302 BC63-1306 BC63-1338 BC62-719 BC62-454 BC62-678 BC62-488 BC62-451 BC62-657 BC62-547 BC62-499 BC63-1303 BC63-1299 BC63-1301 BC63-1376 BC62-528 BC62-50O BC62-661 BC62-484 BC62-651 7 Kanatak, Portage Bay 57°36'N. 154°30'W. 56°42 ,00"N. 154o30'00"W. 58°03'N. 154°15'W. 56°45'N„ 154°15'W. 56°48'N. 154°30'W. 56 G42'N. 15'4°.30'W. 5 7 o36'00"N. 154°30«00"W. 57°42'N. 154°00'W. Kodiak I s l a n d , C h i e f Cove, S p i r i d o n Bay Kodiak I s l a n d , Uyak Bay Kodiak I s l a n d , Uyak Bay 54°53'N„ 155°00'W. 57°09'N o 152°45»W. 57°06'N„ 152°30'W. 57°24'N. 152°30'W. Kodiak I s l a n d , Region I s l a n d , Woody I s l a n d Channel Kodiak I s l a n d , Kodiak Hbr. Kodiak I s l a n d , C h i n i a k Bay, SW beach K a l s i n I s l a n d 57°54'N„ 152°00'W„ Afognak I s l a n d , K i t o i Bay Kachemak Bay Kachemak Bay Kachemak Bay, K a s i t s n a Bay, near crab l a b . 82. f a t h . 140 f a t h , 30 f a t h . 36 f a t h . 18 f a t h . 71 f a t h . 71 f a t h . 0-3 f t . 84 f a t h . 81 f a t h . 54 f a t h . 25 f t . 20 f t . 110 f a t h . 0-30 f t . 12-16 f t . T i d e p o o l s 0-10 f t . BC63' BC62' BC62' BC62 BC62 BC62 BC62 BC62' BC62 BC59' •1164 •676 •530 -514 -481 -680 -683 •503 •679 -485 BC59-486 BC62-555 BC62-643 BC62-453 BC62-677 BC62-684 BC63-1026 BC62-1027 BC63-1032 BC62-660 BC58-209 BC61-520 BC61-521 BC62-991 8 Upper Kachemak Bay, 1 mi. E. Homer S p i t Kachemak Bay, Tulka Bay 59°30*N. 151°30'W. Kachemak Bay, K a s i t s n a Bay E l r i n g t o n I s l a n d , P r i n c e W i l l i a m Sound Galena Bay, Pr i n c e W i l l i a m Sound W shore Olsen near mouth, P r i n c e W i l l i a m Sd. Pri n c e W i l l i a m Sd., Olsen W shore near mouth Port Gravina, P r i n c e W i l l i a m Sd. 14 f a t h . I n t e r t i d a l T i d e p o o l BC62-995 BC62-998 BC63-109 BC63-118 BC63-128 BC63-484 BC63-434 BC63-474 BC63-385 Southeast A l a s k a Chichagof I s l a n d , Whitestone Hbr. Auke Bay, o f f Coghland I s l a n d Auke Bay, o f f Coghland I s l a n d Auke Bay, o f f Coghland I s l a n d Barlow Cove, N end o f A d m i r a l t y I s l a n d Barlow Cover, S end of P o r t l a n d I s l a n d Horse I s l a n d , Stephens Passage 1 mi. W H i l d a P o i n t , o f f Douglas I. Gastineau Channel, Juneau Young Bay, Stephens Passage Thomas Bay, F r e d r i c k Sd. 0-3 f t . 50-75 f a t h . 100 f t . 8 f a t h . 30 f a t h . 20 f t . 35 f a t h , BC65-139 BC62-611 BC62-612 BC62-969 BC63-189 BC63-78 BC62-791 BC65-138 BC61-511 BC63-325 BC61-544 9 Saginaw Bay-Chatham S t r a i t , F o r e f i n g e r Bay Kuiu I s l a n d , E lana Bay Baranof I., P o r t Walter, back of Clam I . Baranof I., Port Walter, back o f Clam I . Baranof I., Torpedo Hbr. Baranof I., L i t t l e P o r t Walter Baranof I . , P o r t Armstrong C r a i g , boat Hbr. 0-6 f t . 30-40 f t . 30-40 f t . BC63-200 BC62-557 BC63-1290 BC63-261 BC63-262 BC63-1250 BC63-1256 BC62-591 BC63-171 B r i t i s h Columbia Queen C h a r l o t t e C i t y , o f f boat dock 3 f a t h . Creek e s t u a r y 1 mi. W. Aero, Q.C.I. 0-4 f t . G i l l e t t Arm, 3/4 mi. W. Aero, Q.C.I. 50-60 f t . N. corner of Lagoon I n l e t , Q.C.I. Port John, near B e l l a B e l l a Joassa Channel Dean Channel, o f f r i v e r drainage Hope I s l a n d , B u l l Hbr. 50 f t . Queen C h a r l o t t e Sd., W N a h w i t t i Bar Vancouver I s l a n d , P o r t Hardy Georgia S t r a i t , Echo Bay Vancouver I s l a n d , Qualicum Beach Vancouver, E n g l i s h Bay 20 f a t h . BC61-58 BC60-413 BC60-416 BC60-429 BC55-386 BC63-232 BC61-288 BC63-780 BC63-782 BC53-265 BC53-156 BC61-601 BC53-56 10 Vancouver, S t a n l e y Park BC53-273A Vancouver,. S t a n l e y Park 0-3 f t . BC55-357 Vancouver, below second narrows 0-3 f t . BC56-9 Vancouver, S t a n l e y Park 0-2 f a t h . BC58-574 S a l t s p r i n g I s l a n d , F u l f o r d Hbr. BC62-82 Georgia S t r a i t , between N and S BC55-117 Pender I s . Saturna I s l a n d 1 f a t h . BC54-447 Saturna I s l a n d 1 f a t h . BC54-453 Saturna I s l a n d , Saturna Beach 1 f a t h . BC55-119 Saturna I s l a n d 0-•2 f a t h . BC56-83 Saturna I s l a n d , Campbell Beach 0-•1.5 f a t h . BC57-204 Saturna I s l a n d , Campbell Beach 0-•1 f a t h . BC57-205 Saturna I s l a n d , Campbell Beach 0-•1 f a t h . BC57-206 Saturna I s l a n d , Rocky Cove N 0-•2 f a t h . BC57-210 Breezy Bay Saturna I s l a n d , Campbell Beach 0-1 f a t h . BC57-211 Saturna I s l a n d , Breezy Bay 0-20 f t . BC57-213 Saturna I s l a n d , Campbell Beach 0-8 f t . BC57-214 Saturna I s l a n d , Campbell Beach 0-8 f t . BC57-215 NW end Samuel I., o f f Saturna I. BC60-325 Saturna I s l a n d BC60-334 South Pender I s l a n d BC61-267 Vancouver I s l a n d , o f f V i c t o r i a BC60-259 Vancouver I s l a n d , V i c t o r i a , Shoal 7 f t . BC62-853 Bay Vancouver I s l a n d , Sooke BC62-857 11 Vancouver I s l a n d , Vancouver I s l a n d , R i v e r Vancouver I s l a n d , Vancouver I s l a n d , Vancouver I s l a n d , Sooke, Agate Beach Sooke and Jordan Sooke, Agate Beach Sooke, Agate Beach Sooke, Agate Beach Washington, U.S.A. Between F r i d a y Hbr. and l a b . San Juan I s l a n d , Spieden Channel 0-2 f a t h . F a l s e Bay (sand bar) 0-1 f a t h . M a r v i s t a , j u s t below boat ramp 0-1 f a t h . M a t e r i a l Examined - Myoxocephalus iaok Okhotsk Sea 52°43'N. 155°24'E. 30 f a t h . B e r i n g Sea Norton Sound Norton Sound 60°54'N. 179°44'W. 330-390 m. 60°29»N. 178°44'W. 270-390 m. 60°29'N. 176°32'W. P r i b i l o f I s l a n d s , 130 m i l e s NE S t . Paul I s l a n d BC62-871 BC62-872 BC62-874 BC62-880 BC62-882 BC58-336 BC60-336 BC55-373 BC55-374 BC63-670 U.Wash.14250 U.Wash.16385 BC63-684 BC63-690 BC63-398 BC62-560 12 B r i s t o l Bay, Togiak Bay, near Summit I. BC61-3 58°30«N. 157°30'W. BC58-306 Izembek Bay, o p p o s i t e DEWline s i t e 0-1 m„ BC63-1433 Izembek Bay, o p p o s i t e DEWline s i t e 2.5 m. BC63-1438 A l e u t i a n I s l a n d s and Ala s k a n P e n i n s u l a 55°00 I30"N o 163°02'00"W. 47 f a t h . BC62-546 54 G54'00 , ,N. 163o00'W. 45-53 f a t h . BC62-498 54 G33'30"N. 162°29'30"W. 142 m. BC62-440 C o l d Bay, west shore,, o f f dock 15-20 f t . BC63-1079 55°13 ,30"N. 161°47'00"W. 57-60 f a t h . BC62-719 55°36 800"N. 161G28'30"W. 15 f a t h . BC62-489 54°48 1N. 160°00«W. 58 f a t h . BC62-657 55°16'N. 159°40'00"W. 71 f a t h . BC63-505 57° 3.6'-N. 154°30'W. 71 f a t h . BC62-676 56°45«N. 154°15'W. 30 f a t h . BC62-481 58 o30'N. 153°30 ,W„ 83 f a t h . BC62-666 58°36'N. 153°30'W. 58 f a t h . BC62-686 58°55.7'N. 152°57„3'W. 89-91 f a t h . BC65-158 5 4 0 5 4 1 N o 163 o00«W o 53 f a t h . BC62-655 5 7°09 ,N. 152°45'W. 84 f a t h . BC62-453 5 7°06«N. 152°30«W. 81 f a t h . BC62-677 Region I s l a n d , Woody I s l a n d Channel, near Kodiak BC63-1026 Kachemak Bay 4-28 f a t h . BC61-515 13 Kachemak Bay, o f f Homer S p i t Kachemak Bay, Aurora Lagoon Kachemak Bay, K a s i t s n a Bay 54°39'N. 150°45'W. 6-18 f a t h . BC61-517 37-45 f a t h . BC62-998 I n t e r t i d a l BC63-118 63 f a t h . BC62-678 Method of Measurement The standa r d l e n g t h was measured w i t h a metre r u l e and taken to the n e a r e s t m i l l i m e t r e . A l l o t h e r measurements were made u s i n g e i t h e r d i a l c a l i p e r s o r d i v i d e r s and r u l e r , and taken to the n e a r e s t t e n t h o f a m i l l i m e t r e . Some d i f f i c u l t i e s were encountered i n making the s e v e r a l measurements of depths and widths o f the body. For the most p a r t t h i s was a t t r i b u t a b l e fi-o the s t a t e o f p r e s e r -v a t i o n o f the specimens and to the p l a s t i c i t y o f the abdominal r e g i o n . D e f i n i t i o n o f Measurements Standard l e n g t h i s the d i s t a n c e from the most a n t e r i o r t i p o f the snout to the s t r u c t u r a l base of the ca u d a l f i n . Snout•length i s the d i s t a n c e from the most a n t e r i o r t i p o f the snout to the a n t e r i o r margin of the o r b i t . Head l e n g t h i s the d i s t a n c e from the most a n t e r i o r t i p o f the snout to the most p o s t e r i o r p a r t l o f the o p e r c u l a r f l a p . M a x i l l a l e n g t h i s the d i s t a n c e from the symphysis o f the p r e m a x i l l a e to the most p o s t e r i o r p a r t o f the m a x i l l a Vomer width i s the d i s t a n c e between the p o s t e r i o r most t i p s o f the two wings o f the vomer. I n t e r o r b i t a l width i s the l e a s t d i s t a n c e between the two o r b i t s . I n t e r o r b i t a l depth i s the maximum p e r p e n d i c u l a r d i s t a n c e from a h o r i z o n t a l plane ac r o s s the o r b i t s to the d o r s a l mid l i n e o f the f r o n t a l bones. Eye Diameter i s the g r e a t e s t d i s t a n c e between the f r e e o r b i t a l r i m s . 1 s t p r e d o r s a l l e n g t h i s the d i s t a n c e from the a n t e r i o r most t i p of the snout to the s t r u c t u r a l base of the f i r s t d o r s a l s p i n e . 2nd p r e d o r s a l l e n g t h i s the d i s t a n c e from the a n t e r i o r most t i p o f the snout to the s t r u c t u r a l base o f the a n t e r i o r most 2nd d o r s a l f i n r a y . Preanal l e n g t h i s the d i s t a n c e from the a n t e r i o r most t i p o f the snout"to the s t r u c t u r a l base o f the f i r s t a n a l r a y . P r e p e l v i c l e n g t h i s the d i s t a n c e from the a n t e r i o r most t i p of the snout to the s t r u c t u r a l base o f the l a t e r a l most p e l v i c r a y . 1st d o r s a l f i n base i s the d i s t a n c e from the 15 s t r u c t u r a l o r i g i n of the anterior most dorsal spine to the posterior most dorsal spine. 2nd dorsal f i n base i s the distance from the st r u c t u r a l o r i g i n of the anterior most anal f i n ray to the st r u c t u r a l base of the l a s t second dorsal ray„ •Anal f i n base i s the distance from the s t r u c t u r a l base of the anterior most anal ray to the s t r u c t u r a l base of the l a s t ray. Pectoral f i n base i s the distance between the str u c t u r a l o r i g i n of the dorsal most and ventral most. rays. Depth at pectorals i s the maximum height of the body taken i n a v e r t i c a l plane from the o r i g i n of the 1st dorsal f i n . Width at pectorals i s the maximum distance between l a t e r a l surfaces of the body taken i n the horizontal plane between the two scapular bones. Depth at anus i s the maximum height of the body taken i n the v e r t i c a l plane of the anus. Width- at anus i s the maximum distance between the l a t e r a l surfaces of the body taken i n the horizontal plane of the anus. Depth of caudal peduncle i s the le a s t height of the body taken i n the v e r t i c a l plane between the so f t dorsal f i n and the base of the caudal f i n . Width of caudal peduncle i s the distance between 16 the l a t e r a l s u r f a c e s o f the body taken i n the h o r i z o n t a l plane o f the l e a s t depth o f the caudal peduncle. Length of l o n g e s t p e c t o r a l r a y i s the d i s t a n c e from the s t r u c t u r a l base o f the l o n g e s t p e c t o r a l f i n r a y to i t s t i p . Length o f l o n g e s t . p e l v i c r a y i s the d i s t a n c e from the s t r u c t u r a l base o f the l o n g e s t p e l v i c r a y to i t s t i p . Length o f l o n g e s t 1 s t d o r s a l spine i s the d i s t a n c e from the s t r u c t u r a l base o f the l o n g e s t spine to i t s t i p . Length of l o n g e s t 2nd d o r s a l r a y i s the d i s t a n c e from the s t r u c t u r a l base o f the l o n g e s t 2nd d o r s a l ray. to i t s t i p . Length of l o n g e s t c a u d a l ray i s the d i s t a n c e from the s t r u c t u r a l base of the l o n g e s t caudal r a y to i t s t i p . Length o f l o n g e s t a n a l ray i s the d i s t a n c e from the s t r u c t u r a l base o f the l o n g e s t a n a l r a y to i t s t i p . Length o f the p r e o p e r c u l a r spine i s the d i s t a n c e between the t i p of the f i r s t p r e o p e r c u l a r spine and the apex o f the angle formed by the f i r s t and second p r e o p e r c u l a r s p i n e s . P r e o p e r c u l a r l e n g t h i s the d i s t a n c e between the d o r s a l base of the f i r s t p r e o p e r c u l a r spine and the t i p of the f o u r t h p r e o p e r c u l a r s p i n e . Length of r o s t r a l c a r t i l a g e i s the d i s t a n c e from the symphysis of the p r e m a x i l l a e to the p o s t e r i o r most end of the r o s t r a l c a r t i l a g e . 17 S u b o r b i t a l s t a y l e n g t h i s the d i s t a n c e from the a n t e r i o r most p a r t o f the a r t i c u l a t i o n o f the s u b o r b i t a l s w i t h the p r e f r o n t a l bone to the p o s t e r i o r most t i p o f the s u b o r b i t a l s t a y . . M e r i s t i c C h a r a c t e r s  F i n Ray Counts In the r a y counts taken on the second d o r s a l and an a l f i n s , the s p l i t rays o f f the l a s t b a s a l s were counted as two d i s t i n c t elements. V e r t e b r a l Counts V e r t e b r a l counts were made from x-ray f i l m s and from c l e a r e d and s t a i n e d m a t e r i a l i n the case of some of the small, i n d i v i d u a l s . The h y p u r a l elements were excluded from the counts. L a t e r a l Line Pore Counts The number of l a t e r a l l i n e pores was not a c t u a l l y counted s i n c e numerous pores are g i v e n o f f from each secondary c a n a l . Due to t h i s s i t u a t i o n the number o f l a t e r a l l i n e o s s i c l e s was counted. 18 C l e a r i n g and S t a i n i n g Technique F i v e M. polyacanthocephalus and two M. iaok were s t a i n e d and c l e a r e d f o r anatomical s t u d i e s . The s k i n s o f f o u r M. polyacanthocephalus and f i v e M. iaok o f v a r i o u s s i z e s were s t a i n e d and c l e a r e d f o r s t u d i e s o f the l a t e r a l l i n e o s s i c l e s , the squamation, and the s i z e a t which these s c a l e s f i r s t form. The c l e a r i n g and s t a i n i n g technique used was m o d i f i e d from t h a t o f C l o t h i e r (1950). The specimens and s k i n s were f i r s t washed i n running water f o r a p e r i o d o f one day and then put i n t o a s o l u t i o n o f 10% hydrogen peroxide f o r 1-2 hours, o r u n t i l the integumental pigment was f a i r l y w e l l b l e a c h e d o u t . The specimens were then removed, washed and put i n t o a one l i t r e vacuum f l a s k h a l f f i l l e d w i t h water. The f l a s k was then evacuated by means of tap s u c t i o n f o r about f o u r hours o r u n t i l bubbles were no lo n g e r b e i n g e m i t t e d from the specimens. They were then p l a c e d - i n a s o l u t i o n o f 4% potassium hydroxide c o n t a i n i n g s u f f i c i e n t a l i z e r i n e r e d to form a l i g h t p u r ple s o l u t i o n . The specimens remained i n the s t a i n i n g s o l u t i o n f o r about 10-24 hours depending on the s i z e o f the m a t e r i a l . The s t a i n e d m a t e r i a l was then p l a c e d f o r a p e r i o d o f one day i n each of f i v e s o l u t i o n s o f g l y c e r i n e i n 4% potassium hydroxide, 30%, 50%, 70%, 80%, 90% r e s p e c t i v e l y . I f a t the end of t h i s time the specimens were s u f f i c i e n t l y c l e a r e d , they were put i n t o 100% g l y c e r i n e f o r s t o r a g e . I f they were not 19 s u f f i c i e n t l y c l e a r e d , they were allowed to remain i n the 90% g l y c e r i n e s o l u t i o n u n t i l the d e s i r e d degree o f c l a r i t y was a t t a i n e d . O s t e o l o c r i c a l P r e p a r a t i o n The s k e l e t o n s o f both M. polyacanthocephalus and M. iaok were prepared from p r e s e r v e d specimens. The s k i n and most o f the muscle and c o n n e c t i v e t i s s u e was removed by d i s s e c t i o n . The rough p r e p a r a t i o n was then p l a c e d i n t o a 50% s o l u t i o n o f b l e a c h ("Perfex") f o r 10-35 minutes to remove the remaining muscle and c o n n e c t i v e t i s s u e . The s k e l e t o n was then put i n t o a weak s o l u t i o n o f ammonium hydroxide so as to n e u t r a l i z e the b l e a c h . I t was then b l e a c h e d i n 35% hydrogen peroxide f o r 5-20 minutes, washed i n water and allowed to dry. X-Ray Technique To f a c i l i t a t e the c o u n t i n g o f v e r t e b r a e , x-rays were used. The x-rays were taken w i t h a General E l e c t r i c model D - l X-Ray u n i t u s i n g I l f o r d I l f l e x X-Ray f i l m . Exposures were taken w i t h the cone o f f , the r a y source a t maximum e l e v a t i o n (132 cm), f i l a m e n t s e t t i n g 3, and v o l t a g e s e t t i n g 3. The exposure times v a r i e d from 3 seconds f o r 20 s m a l l i n d i v i d u a l s to 10 seconds f o r l a r g e ones. F i l m was processed u s i n g General E l e c t r i c Supermix developer and f i x e r s o l u t i o n s . To ensure uniform d r y i n g , the washed f i l m s were r i n s e d i n Kodak Photo-Flo s o l u t i o n f o r 30 seconds p r i o r to d r y i n g . E l e c t r o p h o r e t i c Technique E l e c t r o p h o r e s i s i s the movement o f charged c o l l o i d a l p a r t i c l e s i n s o l u t i o n under the i n f l u e n c e o f an e l e c t r i c f i e l d . The technique r e l i e s on the d i f f e r e n t i a l e l e c t r i c a l p o t e n t i a l s o f the p r o t e i n molecules and thus on t h e i r d i f f e r e n t m i g r a t i o n r a t e s i n a uniform f i e l d . The technique was i n t r o d u c e d by T i s e l i u s (1937) who used f r e e e l e c t r o p h o r e s i s . Since then more s o p h i s t i c a t e d techniques have been developed. These have i n c o r p o r a t e d d i f f e r e n t s u p p o r t i n g s u b s t r a t e s through which the p a r t i c l e s t r a v e l . The f i r s t m o d i f i c a t i o n was t h a t o f paper e l e c t r o p h o r e s i s . L a t e r Smithies (1955, 1959) found t h a t remarkable r e s o l u t i o n c o u l d be a c h i e v e d when s t a r c h g e l was used as the s u p p o r t i n g s u b s t r a t e . T h i s method takes advantage o f the f r i c t i o n a l p r o p e r t i e s of the g e l to a i d i n s e p a r a t i o n by s i e v i n g a t the m o l e c u l a r l e v e l . S m ithies' method s t i m u l a t e d the development o f y e t a more r e f i n e d technique, named d i s c e l e c t r o p h o r e s i s , by O r n s t e i n (1964), which uses a p o l y a c r y l a m i d e g e l as a s u b s t r a t e . In 21 the case o f s t a r c h g e l and d i s c e l e c t r o p h o r e s i s the temperature, v o l t a g e , and the u n i f o r m i t y o f the g e l s u b s t r a t e s are of c r i t i c a l importance. In t h i s study, s t a r c h g e l e l e c t r o p h o r e s i s was used f o r muscle p r o t e i n a n a l y s i s . Three muscle samples from each M. polyacanthocephalus and M. iaok were submitted f o r a n a l y s i s . The analyses were performed by Dr. H. Tsuyuki o f the T e c h n o l o g i c a l S t a t i o n o f the F i s h e r i e s Research Board o f Canada, Vancouver, u s i n g a m o d i f i e d s t a r c h g e l technique as d e s c r i b e d by Tsuyuki e t a l (1965). The s t a i n e d g e l s were photographed by the E x t e n s i o n Department of the U n i v e r s i t y of B r i t i s h Columbia under standar d c o n d i t i o n s designed to y i e l d n e g a t i v e s t h a t would be s t r i c t l y comparable f o r a n a l y s i s o f d e n s i t y and m o b i l i t y . S t a t i s t i c a l Technique The s t a t i s t i c a l a n a l y s i s o f the data was r e s t r i c t e d to the c a l c u l a t i o n o f those means, standar d d e v i a t i o n s and standard e r r o r s which were necessary i n the c o n s t r u c t i o n o f the type o f g r a p h i c a l comparison used by Hubbs and Hubbs (1953) . P r e l i m i n a r y analyses o f the measurements o f the body were made a t the U n i v e r s i t y o f B r i t i s h Columbia Computing Center u s i n g the I.B.M. 7040 computer. In the 22 program used ;each measurement was transformed into a percentage of each other body measurement. The maximum and minimum values of these percentages were printed out. This treatment of the 32 measurements yielded 992 combinations f o r comparison. It was thus possible by c a l c u l a t i n g the amount of percentage overlap between the two species, to evaluate each body measurement as a taxonomic character. 23 RESULTS C o l o r a t i o n o f M. p o l y a c a n t h o c e p h a l u s The g e n e r a l body c o l o r i s dark, b l a c k i s h on the d o r s a l s u r f a c e , becoming m o t t l e d v e n t r a d . The v e n t r a l s u r f a c e i s p a l e , f o r the most p a r t unpigmented w i t h a few s c a t t e r e d groups o f melanophores. Four, more o r l e s s d i s t i n c t , dark, i r r e g u l a r b a r s a r e u s u a l l y p r e s e n t on the body. The f i r s t b a r o r i g i n a t e s on the s p i n o u s d o r s a l f i n between the f i f t h and n i n t h s p i n e s , c o u r s e s o b l i q u e l y a n t e r o v e n t r a l l y , t e r m i n a t i n g j u s t below and b e h i n d the d o r s a l o r i g i n o f the p e c t o r a l f i n b a s e . The second b a r commences a t the base o f r a y s f o u r t o seven o f the s o f t d o r s a l f i n r u n n i n g a l m o s t d i r e c t l y v e n t r a d u n t i l i t c r o s s e s the l a t e r a l l i n e . I t th e n runs o b l i q u e l y a n t e r o v e n t r a d , t e r m i n a t i n g above and b e h i n d the anus about l e v e l w i t h the v e n t r a l e x t e n t o f the f i r s t b a r . The p o s t e r i o r b o r d e r o f t h i s b a r i s not always w e l l d e f i n e d . The t h i r d b a r commences a t the base o f the t h i r t e e n t h t o f i f t e e n t h s o f t d o r s a l r a y s and runs o b l i q u e l y a n t e r o v e n t r a d t e r m i n a t i n g somewhat above the a n a l f i n b a s e . The a n t e r i o r m a r g i n o f t h i s b a r i s not always w e l l d e f i n e d . O c c a s i o n a l l y the t h i r d and second b a r s appear t o merge i n t o one l a r g e b a r however even where t h i s o c c u r s t h e r e . i s o f t e n a d e f i n i t e l i g h t e n i n g between the two. The l a s t b a r b e g i n s 2 4 between the a n t e r i o r e x t e n t of the d o r s a l f i n r a y l e t s and the base o f the caudal f i n . T h i s bar runs more o r l e s s v e r t i c a l l y a c r o s s t h i s a r e a . C o l o r a t i o n of__the back i s r e l a t i v e l y dark on the nape and as f a r as the f i r s t bar, and tends, to become p r o g r e s s i v e l y p a l e r i n the i n t e r s p a c e s between b a r s . The c a u d a l peduncle i s p a l e . In some cases the p r e v i o u s l y d e s c r i b e d dark bars appear to become the back-ground and the p a l e r i n t e r s p a c e s the b a r s . The v e n t r a l margin.of the pigmentation i s v e r y i r r e g u l a r , o f t e n b e i n g broken up i n t o s e m i c i r c u l a r and o c c a s i o n a l l y c i r c u l a r p a t t e r n s o u t l i n i n g nonpigmented a r e a s . The a n t e r i o r p o r t i o n of the spinous d o r s a l . f i n i s m o t t l e d w i t h dark pigment. P o s t e r i a d most o f the pigment i s r e s t r i c t e d to the s k i n c o v e r i n g the spines w h i l e the i n t e r s p i n o u s membranes are r e l a t i v e l y unpigmented. The a n t e r i o r most bar on the body i s p r o j e c t e d i n t o t h i s f i n from betwen the f i f t h and n i n t h s p i n e s , c o v e r i n g almost a l l of the f i f t h and p r o g r e s s i v e l y l e s s of the s i x t h to n i n t h spines„ The second d o r s a l f i n ; i s v a r i a b l e i n i t s c o l o r a t i o n . The pigmentation i s u s u a l l y more o r l e s s r e s t r i c t e d to the r a y s . O f t e n two dark bands are encountered, one r e l a t i v e l y b road b a s a l band commencing and b e i n g b r o a d e s t a n t e r i o r l y and d e c r e a s i n g i n breadth p o s t e r i a d . The second, more d o r s a l , band i s u s u a l l y excluded from the f i r s t two o r three rays and 25 i n c r e a s e s i n breadth p o s t e r i a d . The c o l o r a t i o n o f the caudal f i n a l s o e x h i b i t s a g r e a t d e a l of v a r i a t i o n . I t u s u a l l y has a pale patch a t the base of the more i n t e r n a l r a y s . Beyond t h i s patch a broad dark v e r t i c a l bar i s o f t e n found, which may extend out three q u a r t e r s of the l e n g t h o f the r a y s . J u s t a n t e r i o r to the t i p s of the rays another narrower band of dark pigment i s o c c a s i o n a l l y p r e s e n t . Pigmentation on the c a u d a l f i n i s g e n e r a l l y r e s t r i c t e d to the rays, the membranes b e i n g almost d e v o i d of i t . In many:instances the c o l o r a t i o n i s composed o f i r r e g u l a r s e r i e s o f b l o t c h e s . The a n a l f i n i s e s s e n t i a l l y nonpigmented b u t bears three d i s t i n c t dark bars c o u r s i n g a n t e r o v e n t r a d from i t s base. There i s o f t e n an a d d i t i o n a l dark b a r on the t i p s o f the p o s t e r i o r most three to s i x r a y s . P e c t o r a l f i n c o l o r a t i o n i s v a r i a b l e . In g e n e r a l the base i s r e l a t i v e l y dark d o r s a l l y becoming l i g h t e r v e n t r a d . There i s o f t e n a dark band on the proximal t h i r d o f the r a y s . More d i s t a l l y the pigmentation i s v e r y e r r a t i c o f t e n forming i r r e g u l a r b l o t c h e s and i n some cases d i s t i n c t bands. The p e l v i c f i n s are o f t e n d e v o i d of pigment b u t some have-one to three p a l e b a r s a c r o s s the f i n that, are more i n t e n s e i n mature males, (Sexual dimorphism.is e x h i b i t e d . i n p e l v i c f i n c o l o r a t i o n and w i l l be c o n s i d e r e d i n a l a t e r s e c t i o n ) , The c o l o r a t i o n - o f the top of the head, cheeks and 2 6 o p e r c u l a r r e g i o n s i s dark. The d o r s a l l i p i s dark above becoming somewhat.lighter and s p e c k l e d below. The membrane between the p r e m a x i l l a and the m a x i l l a i s b l o t c h y and o f t e n v e r m i c u l a t e d w i t h dark pigment. The m a x i l l a i s dark d o r s a l l y l i g h t e n i n g v e n t r a l l y and o n . i t s f r e e end. The lower l i p o f t e n bears a number o f d i s t i n c t b a r s c o u r s i n g a c r o s s the l i p . In many cases i t . i s b l o t c h e d or s p e c k l e d . The mandibular r e g i o n i s r e l a t i v e l y dark on the l a t e r a l s u r f a c e l i g h t e n i n g mediad. The b r a n c h i o s t e g a l membranes are dark d o r s a l l y becoming l i g h t e r v entrad, the isthmus and h y o i d r e g i o n b e i n g almost devoid-of pigment. Comparison of C o l o r a t i o n o f M. polyacanthocephalus and M. Iaok The c o l o r a t i o n o f M. Iaok i s d i s t i n c t from t h a t o f M. polyacanthocephalus. The g e n e r a l body c o l o r a t i o n of M. iaok i s l i g h t brown to tan w i t h numerous b l a c k b l o t c h e s , spots, s p e c k l e s and v e r m i c u l a t i o n s . In younger i n d i v i d u a l s the c o l o r a t i o n tends to be l e s s i n t e n s e and w i t h fewer spots and s p e c k l e s : t h a n \ i n a d u l t s . The v e n t r a l s u r f a c e , as i n M. polyacanthocephalus. i s almost d e v o i d o f pigment. U n l i k e M. polyacanthocephalus the c o l o r p a t t e r n i s r e l a t i v e l y uniform throughout the l e n g t h of the body and'no bars are p r e s e n t . Below the l a t e r a l l i n e pigmentation l e s s e n s v e n t r a l l y u n t i l h a l f way between the l a t e r a l l i n e and the mid v e n t r a l l i n e 27 the s k i n i s almost c o l o r l e s s . The spinous d o r s a l f i n has i r r e g u l a r , pale b l o t c h e s of dark pigment. The more d i s t a l p o r t i o n s o f the spines are o f t e n almost b l a c k . The second d o r s a l f i n i s a l s o l i g h t l y -b l o t c h e d w i t h dark pigment, o f t e n some o f the b l o t c h e s becoming c o n f l u e n t . In many eases there i s a narrow b l a c k band running a l o n g the d i s t a l margin o f the f i n . The c a u d a l f i n c o l o r a t i o n i s v a r i a b l e . T h i s f i n o f t e n has a s e r i e s of three or f o u r dark bands s e p a r a t e d by r e l a t i v e l y unpigmented ar e a s . There may however be no bars and j u s t s m a l l i r r e g u l a r b l o t c h e s . M. iaok appears to l a c k the f a i r l y c h a r a c t e r i s t i c unpigmented patch a t the base o f the caudal f i n and a l s o the wide dark band possesed by most of the M. polyacanthocephalus„ The a n a l f i n i s s i m i l a r to t h a t o f M. polyacanthocephalus. I t has f o u r to s i x f a i r l y e v e n l y spaced b l a c k bars o r i g i n a t i n g a t i t s base and o r i e n t e d v e r t i c a l l y w h i l e those o f M. polyacanthocephalus are u s u a l l y s l o p e d i n an a n t e r o v e n t r a l d i r e c t i o n . The base o f the p e c t o r a l f i n i s u s u a l l y d e v o i d of pigment w h i l e the f i n i t s e l f i s covered w i t h i r r e g u l a r b l a c k b l o t c h e s . These f r e q u e n t l y become c o n f l u e n t to compose one to s e v e r a l narrow b l a c k bands. The p e l v i c f i n s , as: i n M. polyacanthocephalus, are u s u a l l y almost d e v o i d o f pigment, some having f a i n t b l a c k bars which become i n t e n s i f i e d i n mature males. Sexual dimorphism 28 i s e x h i b i t e d i n p e l v i c f i n c o l o r a t i o n and w i l l be d i s c u s s e d i n the s e c t i o n on Sexual Dimorphism. The top of the head e x h i b i t s much the same c o l o r a t i o n as does the body, however the s p e c k l i n g i s o f t e n f i n e r and more dense. The upper l i p and the m a x i l l a are u s u a l l y dark d o r s a l l y becoming l i g h t e r v e n t r a l l y and may be a l m o s t non-pigmented on the v e n t r a l margins. The membrane between the p r e m a x i l l a and the m a x i l l a d i f f e r s ; f r o m M. polyacanthocephalus i n b e i n g almost t o t a l l y unpigmented. The cheeks and o p e r c u l a r r e g i o n are o f t e n s l i g h t l y l i g h t e r than the top o f the head and o c c a s i o n a l l y patches d e v o i d o f pigment are found. The lower l i p i s o f t e n almost unpigmented b u t may have a few l i g h t b l o t ches; o f dark pigment. T h i s i s another f e a t u r e d i f f e r e n t i a t i n g the two s p e c i e s as i n M. polyacanthocephalus the lower l i p i s h e a v i l y pigmented o r b a r r e d . The mandibular, h y o i d and lower p o r t i o n s o f the b r a n c h i i o s t e g a l r e g i o n s are o f t e n b l o t c h e d i r r e g u l a r l y w i t h white and are almost w h o l l y l a c k i n g b l a c k pigment. In some i n s t a n c e s the whole area may be almost devoid of pigment. D o r s a l l y b r a n c h e o s t e g a l membranes o f t e n have a few s c a t t e r e d areas o f dark and a l s o white c o l o r a t i o n . Sexual Dimorphism i n C o l o r a t i o n o f M. polyacanthocephalus Sexual dimorphism i n c o l o r a t i o n appears t o be common 29 i n M. polyacanthocephalus and i s e x h i b i t e d to some degree by-most o f the mature males. The most predominant d i f f e r e n c e between sexes i s found i n the c o l o r a t i o n o f the p e l v i c f i n s . U s u a l l y the p e l v i c f i n s have one to three d i s t i n c t b l a c k bands t r a v e r s i n g the f i n s . In those females which do possess these bands they are v e r y much f a i n t e r and l e s s w e l l d e f i n e d . In some of the mature males there are b l o t c h e s o f white on p e l v i c s which do not occur on the females. A few o f the mature males have s c a t t e r e d spots o f white on the s i d e s o f the body and on the p e c t o r a l f i n s which have not been seen on the females. Comparison o f Sexual Dimorphism i n C o l o r a t i o n o f  M. polyacanthocephalus and M. iaok Sexual dimorphism i n c o l o r a t i o n i s more pronounced i n M. iaok than- i n M. polyacanthocephalus. • In M. iaok the p e l v i c f i n s o f mature males have, i n most cases,, two to three b l a c k bands c r o s s i n g the rays s i m i l a r to M. polyacan- thocephalus. Between the bands, b l o t c h e s o r spots o f white commonly o c c u r . In a few i n s t a n c e s i n M, iaok the bands on the medial s u r f a c e are i n t e n s e l y b l a c k and se p a r a t e d by narrower bands o f white. In these cases the v e n t r a l s u r f a c e of the spine and o f the most l a t e r a l r a y have the dark pigment g r e a t l y reduced i n i n t e n s i t y . Mature males o f M. 30 polyacanthocephalus and M. iaok both have s c a t t e r e d white spots a l o n g the s i d e s , b u t they are o f t e n more numerous i n the l a t t e r . M. iaok d i f f e r s f u r t h e r from M. polyacanthocephalus i n h a v i n g from one to f o u r white spots along the base o f the spinous d o r s a l f i n . In two specimens the white extended up onto the f i n i t s e l f . Some i n d i v i d u a l s o f M. iaok a l s o have white b l o t c h e s on the second d o r s a l f i n . In one i n s t a n c e the area covered by the p e c t o r a l f i n and a x i l which i s s p a r c e l y pigmented normally was i n t e n s e l y b l a c k w i t h s c a t t e r e d white s p o t s . The p e c t o r a l f i n s o f many mature males of M. iaok as i s found w i t h some o f the M„ polyacantho- cephalus , have a few white spots on them. The C e p h a l i c L a t e r a l L i n e System o f M.. polyacanthocephalus The c e p h a l i c l a t e r a l l i n e system, o f M. polyacantjhocephalus i s complex e s p e c i a l l y i n pore p a t t e r n (Figure 1 and 2). With the e x c e p t i o n o f those on the mandible, the pores are v e r y s m a l l and not r e a d i l y apparent to the naked eye. T h i s o b s c u r i t y i s due i n . p a r t to numerous s m a i r lumps or warts on top o f the head. Sometimes the pores may be d i s c e r n e d by t h e i r unpigmented i n n e r margins. Examination o f se v e r a l ' i n d i v i d u a l s , i n d i c a t e d t h a t the pore p a t t e r n i s v a r i a b l e even between the two s i d e s o f an i n d i v i d u a l . Because of t h i s pore p a t t e r n w i l l not be d e a l t 31 with i n d e t a i l . Only the major canals w i l l be described. The nomenclature used f o r the canals i s that-of Hubbs and Gannon (1935). The cephalic l a t e r a l l i n e system has i t s beginning p o s t e r i o r l y at the point where the body l a t e r a l l i n e canal meets the supracleithrum on i t s dorsomedial surface. From this point the canal passes a n t e r i o r l y through i t and into the posttemporal bone mid way between i t s two points of a r t i c u l a t i o n with the supracleithrum. I t then courses a n t e r i o r l y through the posterior portion of the posttemporal and into a small tabular bone. At the anterior end of th i s tabular bone the canal bifurcates, one branch running anteriad to become the l a t e r a l canal and the other branch running mediad to become the supratemporal canal. The supratemporal canal- passes through another tabular bone and then through the posterior portion of the p a r i e t a l bone beneath the cr e s t and towards the mid dorsal l i n e where i t i s joined by i t s counterpart from the other side. From th i s juncture a smaller canal arises and runs posteriad to just i n front of the spinous dorsal f i n . The l a t e r a l canal courses beneath the p t e r o t i c crest anteriad. When the canal emerges from the p t e r o t i c bone i t bifurcates, one branch passing mediad to form the supraorbital canal and one v e n t r o l a t e r a l l y to become the i n f r a o r b i t a l canal. 3 2 The s u p r a o r b i t a l c a n a l almost immediately e n t e r s the f r o n t a l bone w h e r e . i t passes under the p o s t o r b i t a l c r e s t and c o n t i n u e s around the base of the rim o f the eye. I t leaves the f r o n t a l bone near i t s a n t e r i o r e x t r e m i t y and b i f u r c a t e s . One s m a l l e r c a n a l runs around and over the p o r t i o n of the base o f the o r b i t a l rim c o n t r i b u t e d by the p r e f r o n t a l bone and then t e r m i n a t e s . The o t h e r l a r g e r branch cont i n u e s a n t e r i a d c o u r s i n g through the medial p o r t i o n o f the n a s a l bone and t e r m i n a t i n g j u s t above the upper l i p . The i n f r a o r b i t a l c a n a l passes through s u b o r b i t a l s 5 and 4 and i n t o the s u b o r b i t a l s t a y . A f t e r e n t e r i n g i t , the c a n a l runs a n t e r i a d through i t i n t o the d o r s a l p o r t i o n of the second then the f i r s t ( l a c r i m a l ) s u b o r b i t a l s and terminates a t the a n t e r o d o r s a l p o r t i o n of the l a t t e r . The preoperculomandibular c a n a l has no d i r e c t c o n n e c t i o n w i t h the r e s t o f the c e p h a l i c l a t e r a l l i n e system. I t o r i g i n a t e s on the cheek r e g i o n midway between the l a t e r a l c a n a l and the s u b o r b i t a l s t a y . The c a n a l runs p o s t e r i a d u n t i l i t c r o s s e s over the hyomandibular bone then curves v e n t r o l a t e r a l l y and e n t e r s the proximal end o f the s h a f t o f the p r e o p e r c u l a r bone. I t runs the l e n g t h of the p r e o p e r c l e , leaves i t and courses a n t e r i a d below the v e n t r a l s u r f a c e of the quadrate then e n t e r s the a r t i c u l a r bone s l i g h t l y below the l a t e r a l s i d e o f i t s a r t i c u l a t i o n w i t h the quadrate. A f t e r p a s s i n g o b l i q u e l y a n t e r o m e d i a l l y through the a r t i c u l a r i t runs along the v e n t r a l s u r f a c e o f the dentary f o r a s h o r t d i s t a n c e b e f o r e e n t e r i n g i t . The c a n a l continues around w i t h i n the dentary to the symphysis o f the jaw where i t i s j o i n e d by i t s c o u n t e r p a r t from the o t h e r s i d e . Comparison o f the c e p h a l i c l a t e r a l l i n e systems o f M. polyacanthocephalus and M. iaok r e v e a l e d no s i g n i f i c a n t d i f f e r e n c e s * The L a t e r a l L i n e System o f the Body o f M. polyacanthocephalus The l a t e r a l l i n e system o f the body o r i g i n a t e s a n t e r i o r l y from the proximal p o r t i o n o f the dorsomedial s u r f a c e o f the s u p r a c l e i t h r u m . From t h i s p o i n t i t courses p o s t e r i a d g r a d u a l l y descending on the l a t e r a l s u r f a c e b u t always i n the upper t h i r d o f the body. A t a p o s i t i o n about o p p o s i t e the end o f the s o f t d o r s a l f i n base, i t descends s h a r p l y to a mid l a t e r a L p o s i t i o n then cont i n u e s backwards extending s l i g h t l y onto the caud a l f i n where i t te r m i n a t e s . Through-out i t s l e n g t h the l a t e r a l l i n e i s made up o f s m a l l t u b u l a r o s s i c l e s ( F i g u r e s 3 and 4 ) . In e x t e r n a l appearance the l a t e r a l l i n e i s demarked by a s l i g h t r i d g e i n the s k i n , w i t h a s e r i e s o f t r a n s v e r s e f o l d s o r furrows throughout i t s l e n g t h . I t thus appears as a c h a i n o f r e g u l a r bumps, each bump r e p r e s e n t i n g a n o s s i c l e . 34 Figure 2: Pore Pattern of Cephalic Lateral Line System of M. polyacanthocephalus. Upon close scrutiny i t i s found that an i n d i s t i n c t canal extends obliquely out posterodorsally and posteroventrally from the middle of the bumps on th e i r upper and lower surfaces respectively. These canals are sometimes raised very s l i g h t l y , p e r i o d i c a l l y giving r i s e to pores and usually ending i n a c l u s t e r . The Lateral Line Ossicles; of -M. polyacanthocephalus I t i s generally acknowledged that the tubular o s s i c l e s found i n conjunction with the l a t e r a l l i n e s of many fishes are derived from modified scales. In some of the more generalized c o t t i d s such as the hemilepidotins, the l a t e r a l l i n e o s s i c l e s s t i l l possess, to a variable extent, some of the spinules that are c h a r a c t e r i s t i c of the unmodified scales (Peden, 1964). The condition of the o s s i c l e s ; i n M. polyacantho- cephalus appears to be greatly advanced over those of the Hemilepidotinae insofar as they have no spines, are more elongate, more c l o s e l y associated with adjacent elements, and e x h i b i t some degree of morphological s p e c i a l i z a t i o n along t h e i r lengths. The morphology (Figures 3 and 4) varies to some extent with position, the more anterior o s s i c l e s being larger and more complex than those posteriad. In the more 36 a n t e r i o r o s s i c l e s , the a n t e r i o r end, when observed from a d o r s a l o r v e n t r a l view,, runs o b l i q u e l y out and back, the p o s t e r i o r end runs inwards and forward b u t l e s s o b l i q u e l y , thus i m p a r t i n g a somewhat rhomboidal appearance. Mid way between the l a t e r a l edges o f the ends on the d o r s a l and v e n t r a l s u r f a c e s , a p a i r o f openings occur, the s i d e s o f which are d o r s a l l y and v e n t r a l l y produced r e s p e c t i v e l y forming prominent n i p p l e - l i k e eminences open a t the a p i c e s . The median l i p s o f these-openings are extended beyond the r e s t o f the margin. From each o f these openings the l a t e r a l l i n e extends out f o r a s m a l l d i s t a n c e g i v i n g o f f a v a r i a b l e number o f pores. Comparison o f the L a t e r a l L i n e O s s i c l e s o f  M. polyacanthocephalus and M. iaok The l a t e r a l l i n e o s s i c l e s o f M. iaok are b a s i c a l l y s i m i l a r to those- o f M. polyacanthocephalus (Figures 3 - 5). Although there i s v a r i a t i o n between, i n d i v i d u a l s and between o s s i c l e s o f a s i n g l e i n d i v i d u a l , t here are s e v e r a l f e a t u r e s t h a t separate the two s p e c i e s . In g e n e r a l the o s s i c l e s o f M. iaok are s l i g h t l y more elongate and narrower than those of M. polyacanthocephalus. The major d i f f e r e n c e i s found i n the shape of the openings to the pore c a n a l s . In M, iaok the s i d e s o f the openings do not form the n i p p l e - l i k e 37 protruberanees c h a r a c t e r i s t i c o f M. polyacanthocephalus„ Although the e x i t fenestrum i s s l i g h t l y e l e v a t e d and the medial edge extends beyond the l a t e r a l one, as i t does i n M. polyacanthocephalus, i t d i f f e r s from the l a t t e r i n p o s s e s s i n g a l a t e r a l c o n s t r i c t i o n . S i m i l a r to M. polyacan- thocephalus , as the l a t e r a l l i n e courses p o s t e r i a d , the o s s i c l e s become s m a l l e r and more e v e n l y c y l i n d r i c a l . The Squamation o f M. polyacanthocephalus The squamation o f M. polyacanthocephalus has been much m o d i f i e d from the c t e n o i d s c a l e s found i n many o f the S c l a r o p a r e i . The s c a l e s are reduced i n s i z e and number and have a more r e s t r i c t e d d i s t r i b u t i o n . They do not appear u n t i l a s i z e o f about 16 cm. i n l e n g t h i s a t t a i n e d . The areas o f squamation can be d i v i d e d i n t o two groups; on the b a s i s o f t h e i r p o s i t i o n s r e l a t i v e to the l a t e r a l l i n e . In the area above the l a t e r a l l i n e the s c a l e s form a more o r l e s s d i s t i n c t row j u s t above the l i n e , s t a r t i n g a n t e r i o r l y somewhat behind the o r i g i n o f t*he spinous d o r s a l f i n and extending p o s t e r i a d to a p o s i t i o n j u s t a n t e r i o r to the base o f the caudal f i n . Immediately above t h i s row, a few s c a t t e r e d s c a l e s are u s u a l l y p r e s e n t . In g e n e r a l a l l the s c a l e s o f t h i s area (Figures 6 and 7) are m o r p h o l o g i c a l l y s i m i l a r . They are elongate, h a v i n g an o v a l o r bulb-shaped 38 F i g u r e 3: L a t e r a l L i n e O s s i c l e o f M. p o l y a c a n t h o c e p h a l u s . X l l . 8 ( a n t e r i o r t o t h e l e f t ) F i g u r e 4: The r e l a t i o n s h i p b e t w e e n L a t e r a l L i n e O s s i c l e s i n M. p o l y a c a n -t h o c e p h a l u s . X12.9 ( a n t e r i o r t o l e f t ) F i g u r e 5: L a t e r a l Line O s s i c l e o f M. Iaok. X12.9 ( a n t e r i o r to l e f t ) 40 base which g i v e s r i s e to one or two long s l e n d e r , p o s t e r i o r l y -d i r e c t e d s p i n u l e s t h a t g r a d u a l l y curve outward. Normally these s c a l e s are completely obscured i n envelopes of s k i n o f t e n w i t h o n l y the t i p s o f the s p i n u l e s p r o t r u d i n g . Where they are b u r i e d they are e v i d e n t o n l y as bumps i n the s k i n . In the l a r g e r s c a l e s the s k i n envelopes the spinous p o r t i o n s thus the p o s t e r i o r p a r t s have a f r e e f l a p from which the t i p s o f the s p i n u l e s o f t e n p r o t r u d e . The s c a l e s o f the area below the l a t e r a l l i n e do not appear to be arranged i n rows or i n any s p e c i f i c p a t t e r n . They commence a n t e r i o r l y j u s t b e h i n d the a x i l o f the p e c t o r a l f i n and immediately below the l a t e r a l l i n e . The number o f s c a l e s i n c r e a s e s p o s t e r i a d to a maximum over the a n a l f i n base, then g r a d u a l l y d i m i n i s h e s . The s c a l e s terminate j u s t a n t e r i o r to the caudal f i n base. They are m o r p h o l o g i c a l l y i d e n t i c a l to those above the l a t e r a l l i n e . Comparison o f Squamation o f M. polyacanthocephalus and M. i a o k The squamation o f M. I a o k i s much more m o d i f i e d than i n M. polyacanthocephalus (F i g u r e s 8 and 9 ) . S i m i l a r to t h a t s p e c i e s the s c a l e s do not appear u n t i l the i n d i v i d u a l i s about 15 cm. i n l e n g t h . The area o f squamation i s more r e s t r i c t e d and the number o f s c a l e s fewer than i n M. polyacanthocephalus. 41 Most m o d i f i c a t i o n o f s c a l e s occurs i n the area above the l a t e r a l l i n e . They form a more or l e s s d i s t i n c t s i n g l e row beginning, i n l a r g e r specimens, j u s t above the l a t e r a l l i n e and s l i g h t l y b ehind the o r i g i n o f the spinous d o r s a l f i n and ending immediately a n t e r i o r to the base of the caudal f i n . In s m a l l e r specimens the s c a l e s b e g i n somewhat more p o s t e r i a d . The s c a l e s are e s s e n t i a l l y s u b - c i r c u l a r i n o u t l i n e w i t h 10 or more s p i n u l e s r a d i a t i n g out and up from t h e i r p erimeters (Figure 8a and b ) . Many have an incomplete r i n g o f secondary s p i n u l e s o r i g i n a t i n g from the bases of the ou t e r ones. There i s always a n o n o s s i f i e d spot i n the cen t e r o f the s c a l e . T h i s g e n e r a l type o f s c a l e i s r e f e r r e d to as a s t e l l a t e t u b e r c l e . The p o s t e r i o r most s t e l l a t e t u b e r c l e s are o f t e n not completely s t e l l a t e i n form (Figure 8 c ) . The shape o f these suggests they have not y e t been completely o r g a n i z e d . Examination of c l e a r e d and s t a i n e d s k i n s from i n d i v i d u a l s i n which the s t e l l a t e t u b e r c l e s are j u s t b e g i n n i n g to form r e v e a l s there are two p a t t e r n s o f o s s i f i -c a t i o n . In the f i r s t p a t t e r n which appears to be the l e a s t common, the base of the t u b e r c l e o s s i f i e s f i r s t and subsequently the spines a re formed. In the second and predominant type, o s s i f i c a t i o n commences i n the o u t e r s p i n u l e s and progresses inwards. O c c a s i o n a l l y i t seems 42 apparent t h a t the t u b e r c l e may be composed o f more than one component which subsequently c o a l e s c e . In the area below the l a t e r a l l i n e i n M. ja o k , the s c a l e s appear to be much l e s s m o d i f i e d and are more l i k e those of M. polyacanthocephalus. They are l i m i t e d to a sm a l l zone j u s t v e n t r a l and p a r a l l e l to the l a t e r a l l i n e . There are no d i s t i n c t rows or p a t t e r n s apparent. The morphology o f these s c a l e s tends to v a r y somewhat w i t h t h e i r p o s i t i o n , the more a n t e r i o r ones b e i n g l a r g e r and having as many as f o u r o r f i v e s p i n u l e s p r o j e c t i n g out and back from t h e i r p o s t e r i o r margins. P o s t e r i a d the s c a l e s tend to be reduced i n s i z e and i n number o f s p i n e s , the p o s t e r i o r ones b e i n g v e r y s m a l l and u n i s p i n a t e . Although the s c a l e s of t h i s area are s i m i l a r to those o f H. polyacanthocephalus, a l l but a few of the s m a l l u n i s p i n a t e ones appear morpho-l o g i c a l l y d i s t i n c t from those of M. polyacanthocephalus. The s p i n u l e s o f the s c a l e s o f M. polyacanthocephalus are much more elongate and the s c a l e s g e n e r a l l y have a narrower base than those of M. i a o k . Figure 6: Scale types found i n M. polyacanthocephalus. X17.5 (anterior at bottom) Figure 7: Scales of M. polyacanthocephalus i n s i t u . X l l (anterior to l e f t ) 4 4 Figure 8: Scales from the region above the l a t e r a l l i n e of M. iaok. a. s t e l l a t e tubercle from anterior end; b. from middle; c. from posterior end. 45 Figure 9 : Types of scales found below the l a t e r a l l i n e i n M. Iaok. 4 6 The P e c t o r a l F i n P a p i l l a e o f M. polyacanthocephalus In mature males of M. polyacanthocephalus some o f the rays o f the p e c t o r a l f i n possess w e l l d e f i n e d p a p i l l a e on t h e i r median s u r f a c e (Figure 10). These p a p i l l a e do not occur on the d o r s a l most two to f o u r rays or on the v e n t r a l most s i x to e i g h t r a y s . The p a p i l l a e appear to be w h o l l y r e s t r i c t e d to the d i s t a l h a l f o f the r a y s . D i s s e c t i o n or c l e a r i n g and s t a i n i n g of the p e c t o r a l f i n s r e v e a l s t h a t each p a p i l l a has an o s s i f i e d core which a r i s e s from the medial s u r f a c e o f the proximal p o r t i o n of an a c t i n o t r i c h and extends o b l i q u e l y dorsomediad. There i s a s m a l l d e p r e s s i o n which extends forward to the d i s t a l end o f the a d j a c e n t a c t i n o t r i c h . The core o r i g i n a t e s i n the d i s t a l end o f the d e p r e s s i o n but o f t e n appears to be coming from both o f the a d j a c e n t a c t i n o t r i c h s , which may r e s u l t from secondary c o a l e s c i n g . In g e n e r a l the p a p i l l a e are v e r y v a r i a b l e i n s i z e and form however they are u s u a l l y r e l a t i v e l y e l o n g a t e . In s e v e r a l i n s t a n c e s the core was found to b i f u r c a t e . Comparison o f P e c t o r a l F i n P a p i l l a e o f  M. polyacanthocephalus and M. iaok The s t r u c t u r e and development o f p e c t o r a l p a p i l l a e on mature males of M. iaok (Figure 11) appears to be i d e n t i c a l 47 to t h a t o f M. polyacanthocephalus. There i s however, one important d i f f e r e n c e . In M. Iaok the p a p i l l a e are not l i m i t e d to the d i s t a l h a l f of the ray as they are i n M. polyacantho- cephalus b ut o f t e n occupy a t l e a s t the d i s t a l t w o - t h i r d s o f the r a y . Probaly due to t h e i r more forward e x t e n t the proximal p a p i l l a e (cores) o c c a s i o n a l l y appear to be coa l e s c e d , s i m i l a r to the a c t i n o t r i c h i a o f t h i s r e g i o n . The P e l v i c F i n P a p i l l a e o f M. polyacanthocephalus The p e l v i c f i n s o f some of the mature males o f M. polyacanthocephalus have p a p i l l a e on the median s u r f a c e s o f some of the rays, s i m i l a r to those found on the p e c t o r a l f i n s (See F i g u r e 1 2 ) . Only about a q u a r t e r o f the mature males which have p e c t o r a l p a p i l l a e are found a l s o to possess p e l v i c p a p i l l a e . The p a p i l l a e appear to be w h o l l y r e s t r i c t e d to the d i s t a l t h r e e - e i g h t h s o f the r a y s . In the m a j o r i t y o f i n d i v i d u a l s which possess these s t r u c t u r e s , they are pr e s e n t o n l y on the most medial r a y . A few i n d i v i d u a l s have them on the medial two rays and, i n one i n s t a n c e , on a l l three r a y s . Each p a p i l l a c o n t a i n s an o s s i f i e d core which i n most i n s t a n c e s appear to o r i g i n a t e from the medial s u r f a c e o f the proximal end o f an a c t i n o t r i c h . A t the p o i n t o f F i g u r e 10: P e c t o r a l P a p i l l a e o f a d u l t male M. polyacanthocephalus. F i g u r e 11: P e c t o r a l P a p i l l a e o f a d u l t male M. Iaok. 49 o r i g i n there i s a s m a l l d e p r e s s i o n which extends forward onto the a d j a c e n t a c t i n o t r i c h . Although o c c a s i o n a l l y the p a p i l l a e cores appear to a r i s e from both o f the adj a c e n t a c t i n o t r i c h i a i t i s p o s s i b l e t h a t t h i s i s due to secondary coalescence w i t h the d i s t a l a c t i n o t r i c h . The cores are elongate and extend almost s t r a i g h t up from the medial s u r f a c e o f the r a y . Comparison o f the P e l v i c P a p i l l a e o f  M. polyacanthocephalus and M. iaok The p e l v i c p a p i l l a e found on mature males of M. iaok (Figure 13) appear to be almost i d e n t i c a l to those o f M„ polyacanthocephalus. U n l i k e M. polyacanthocephalus, p e l v i c p a p i l l a e are found on almost every i n d i v i d u a l which possesses p e c t o r a l p a p i l l a e . In M. iaok, the d i s t r i b u t i o n o f the p a p i l l a e on the rays i s l e s s r e s t r i c t e d than on M. polyacanthocephalus, the p a p i l l a e b e i n g present on the d i s t a l f i v e - e i g h t h s o f the r a y . Although the p a p i l l a are r e s t r i c t e d to the most medial two rays, they are sometimes p r e s e n t on a l l three r a y s . The o r i g i n o f the cores o f the p a p i l l a e appear to be the same as those o f M. polyacanthocephalus. However t h e i r form appears to be a much more v a r i a b l e one and b i f u r c a t i o n s and oth e r i r r e g u l a r i t i e s i n shape occur f r e q u e n t l y . In some i n s t a n c e s i n the proximal r e g i o n o f F i g u r e 12: P e l v i c P a p i l l a e o f a d u l t male M. polyacanthocephalus. F i g u r e 13: P e l v i c P a p i l l a e o f a d u l t male M. i a o k . 5 1 the a c t i n o t r i c h , the cores of several papil l a e are coalesced. Spines and Crests on the Head of M„ polyacanthocephalus a. Spines of the Opercular Apparatus It i s generally accepted by many authors that i n the Cottidae, the possession of four spines on the preopercle i s a primitive feature. The s i t u a t i o n i n M. polyacanthocephalus appears to be somewhat advanced i n t h i s regard since there are usually only three well developed spines i n t h i s l o c a t i o n . There i s evidence also that reduction i s proceeding from the posterior end of the series, because i n several individuals although t h i s spine p e r s i s t s and i s well developed, i n the majority examined the t h i r d spine i s greatly reduced and i s represented only by a very low triangular-shaped eminence. The remainder of the spines of the opercular apparatus appear to be constant. The operculum has a single dorsal spine which protrudes a small distance beyond i t s posterodorsal margin. The interopercle has two spine-like processes, only one of which i s evident externally. This spine appears to be a continuation of the anterior margin of the opercle. The other spine originates from the base of the former one, i s directed anteriad, and i s wholly obscured by the skin. The subopercle has a slender spine o r i g i n a t i n g 5 2 from i t s p o s t e r o d o r s a l margin and o r i e n t e d . p o s t e r i a d . T h i s spine and the a n t e r i o r l y d i r e c t e d one from the i n t e r o p e r c l e l i e i n c l o s e a s s o c i a t i o n w i t h one another and are bound together by c o n n e c t i v e t i s s u e . b. Spines and C r e s t s o f the Top o f the Head The most a n t e r i o r spine occurs on the d o r s a l s u r f a c e of the posteromedial p a r t o f the n a s a l bone. I t i s a r e l a t i v e l y s t r o n g one and curves p o s t e r o l a t e r a l l y . F u r t h e r back on the head, and over the p o s t e r i o r p o r t i o n o f the o r b i t , the p o s t o c u l a r c r e s t i s encountered. T h i s c r e s t e x h i b i t s a f a i r amount of v a r i a t i o n i n i t s s i z e and shape. I t o f t e n appears as a clump o f s h o r t , bony, c o a l e s c e d columns u s u a l l y continuous w i t h the r i m o f the o r b i t and becoming s l i g h t l y h i g h e r p o s t e r i a d . In younger i n d i v i d u a l s t h i s c r e s t i s u s u a l l y made up of a s i n g l e b l u n t , broad-based spine o f t e n h a v i n g a s m a l l c i r r u s a t - i t s t i p . The c i r r u s disappears w i t h age. From the p o s t e r i o r face o f the base of the s u p r a o r b i t a l c r e s t two to f i v e i n t e r d i g i t a t i n g r i d g e s r a d i a t e out. In young i n d i v i d u a l s these r i d g e s are u s u a l l y not outwardly apparent i n the s k i n . The d o r s a l s u r f a c e o f the p t e r o t i c bone a l s o bears a c r e s t . I t i s r e l a t i v e l y elongate running, i n an a n t e r i o r p o s t e r i o r d i r e c t i o n and i s made up o f numerous f i n g e r - l i k e p r o j e c t i o n s which u s u a l l y 53 e x h i b i t a more or l e s s c o alescence between them g i v i n g the c r e s t a s e r r a t e d appearance. The p a r i e t a l bone possesses a crest, s i m i l a r to the p t e r o t i c c r e s t . . I t i s a l s o o r i e n t e d a n t e r i o r l y - p o s t e r i o r l y , the p r o j e c t i o n s u s u a l l y i n c r e a s i n g somewhat i n h e i g h t p o s t e r i a d and u s u a l l y h e a v i e r and more pronounced than the p t e r o t i c c r e s t . The o n l y o t h e r spine found on the top o f the head i s the s u p r a c l e i t h r a l s p i n e . T h i s spine o r i g i n a t e s from the d o r s a l s u r f a c e o f the s u p r a c l e i t h r u m and runs p o s t e r i a d u s u a l l y j u s t f l u s h w i t h the s k i n . Comparison o f the Spines and C r e s t s o f the Head o f  M. polyacanthocephalus and M. Iaok a. Spines of the O p e r c u l a r Apparatus The spines o f the operculum, interoperculum, and suboperculum o f M. iaok appear to- be i d e n t i c a l i n s i z e , shape, and p o s i t i o n to those of M. polyacanthocephalus. There are however some d i f f e r e n c e s i n the spines o f the preoperculum. The f i r s t p r e o p e r c u l a r spine i s o f t e n s l i g h t l y longer i n . M. polyacanthocephalus than i n M. iaok. The most important, d i f f e r e n c e i s found i n the t h i r d p r e o p e r c u l a r s p i n e . In M.. iaok t h i s spine i s w h o l l y l a c k i n g ; u s u a l l y i n M. polyacanthocephalus i t i s prese n t i n a rudimentary form, but i n a few specimens i t may be f u l l y developed. 54 b. Spines and C r e s t s o f the Top of the Head The n a s a l and s u p r a c l e i t h r a l spines o f M. iaok appear to be i d e n t i c a l to those o f M. polyacanthocephalus. The p o s t d c u l a r c r e s t i s more spinous i n M. iaok than i n M. polyacanthocephalus, and may be composed o f upto f o u r d i s t i n c t , b l u n t , heavy s p i n e s . The p t e r o t i c c r e s t . i s smoother and more r i d g e - l i k e i n M„ iaok. The p a r i e t a l c r e s t s o f both s p e c i e s are e s s e n t i a l l y s i m i l a r however t h a t of M. iaok appears to be s l i g h t l y more e l e v a t e d . The Muscles of the Cheek Region of M. polyacanthocephalus The muscles o f the cheek r e g i o n of M.. polyacantho-cephalus (Figures 14-16) have remained r e l a t i v e l y unmodified and are s i m i l a r i n number, form and attachment to those of most o f the h i g h e r t e l e o s t s , Owen (1866), Edgeworth (1935). Upon removal of the s k i n and u n d e r l y i n g c o n n e c t i v e t i s s u e l a y e r from the cheek r e g i o n the s u p e r f i c i a l p o r t i o n s of the adductor m a n d i b u l i complex may be seen. The most, s u p e r f i c i a l d o r s a l s l i p i s found immediately beneath the s u b o r b i t a l s t a y and i s almost rhomboid i n shape. I t s f i b e r s pass o b l i q u e l y down across the cheek towards the m a x i l l a r y r e g i o n . T h i s muscle has i t s o r i g i n i n two p l a c e s , d o r s a l l y from a broad f l a t tendon which a r i s e s from an a n t e r o v e n t r a l p r o j e c t i o n on the proximal end o f the hyomandibular, and 5 5 and v e n t r a l l y on the medial s u r f a c e o f the p o s t e r i o r end o f the s u b o r b i t a l s t a y . The m a j o r i t y o f the f i b e r s o f the d o r s a l s u p e r f i c i a l s l i p o r i g i n a t i n g on the hyomandibular i n s e r t by means of a t h i c k heavy tendon m e d i a l l y on the proximal p o r t i o n o f the m a x i l l a * j u s t beneath the d i s t a l end o f the a u t o p a l a t i n e . The other, more v e n t r a l f i b e r s , o r i g i n a t i n g on the hyomandibular together w i t h the f i b e r s o r i g i n a t i n g on the s u b o r b i t a l s t a y g i v e r i s e to a tendon which i n s e r t s on the medial s u r f a c e o f the proximal end of the mandible. T h i s branch a l s o extends a n t e r i o r a l l y a t the tendon-muscle i n t e r p h a s e a l o n g the d o r s a l margin o f the m a x i l l a i n s e r t i n g on the d o r s a l s u r f a c e o f the m a x i l l a j u s t b e h i n d the d i s t a l end o f the a u t o p a l a t i n e . Immediately v e n t r a l to the p o s t e r i o r border of t h i s d o r s a l s u p e r f i c i a l s l i p , and p a r t i a l l y covered by i t , the s u p e r f i c i a l v e n t r a l s l i p can be seen. The v e n t r a l s l i p o r i g i n a t e s on the a n t e r i o r margin, of the d i s t a l h a l f o f the p r e o p e r c l e . I t s f i b e r s pass almost a n t e r i o r l y to i n s e r t . o n the mandible by means o f the same tendon complex as does the s u p e r f i c i a l d o r s a l p o r t i o n . Below the poster©-dorsal' p o r t i o n o f the s u p e r f i c i a l d o r s a l s l i p , a broad l e v a t o r arcus p a l a t i n i i s found c o u r s i n g o b l i q u e l y down and back. (This muscle w i l l be d i s c u s s e d l a t e r i n t h i s s e c t i o n . ) U n d e r l y i n g the l e v a t o r arcus p a l a t i n i and the s u p e r f i c i a l v e n t r a l s l i p o f the adductor m a n d i b a l i a t h i r d deep s l i p o f 5 6 the l a t t e r adductor mandibuli complex i s found. T h i s s l i p i s almost rhomboidal i n shape. I t o r i g i n a t e s on the a n t e r i o r edge of the head and s h a f t o f the hyomandibular and the a n t e r i o r margin o f the p r e o p e r c l e below the d i s t a l end of the hyomandibular. The f i b e r s converge v e n t r a l l y i n s e r t i n g on the mandible by means of the same tendon bundle complex as do the other s l i p s . S l i g h t l y p o s t e r o d o r s a l l y from i t s apex the p o r t i o n o f the d o r s a l s l i p u n d e r l y i n g the v e n t r a l branch fuses w i t h the s u p e r f i c i a l v e n t r a l s l i p and i n s e r t s by means o f a common tendon. Immediately beneath the f l o o r o f the eye socket the adductor arcus p a l a t i n i i s found. I t o r i g i n a t e s on the l a t e r a l s u r f a c e o f the parasphenoid and i n s e r t s on the p o s t e r o d o r s a l p o r t i o n o f the a u t o p a l a t i n e , the d o r s a l margin o f the e n d o p t e r i g o i d , and the d o r s a l p o r t i o n o f the m e t a p t e r i g o i d . Below and p a r t i a l l y covered by the s u p e r f i c i a l d o r s a l s l i p o f the adductor m a n d i b u l i complex the l e v a t o r arcus p a l a t i n i i s found. I t i s composed of two s l i p s . The a n t e r i o r m o s t and l a r g e s t s l i p o r i g i n a t e s on the ant e r o -l a t e r a l s u r f a c e o f the sphenoid, courses o b l i q u e l y posteroventrad, and i n s e r t s on the a n t e r o l a t e r a l margin of the head and s h a f t o f the hyomandibular and proximal h a l f o f the p r e o p e r c l e . The second s l i p o r i g i n a t e s on a s m a l l l a t e r a l o u t c r o p p i n g o f the sphenotic immediately above the s p h e n o t i c a r t i c u l a t i o n o f the hyomandibular and i n s e r t s : o n the head o f the hyomandibular and the d i s t a l p o r t i o n o f the p r e o p e r c l e . 57 Towards t h e i r d i s t a l ends these two s l i p s appear to be c o n f l u e n t . The adductor hyomandibularis i s found immediately beneath the head o f the hyomandibular. I t i s a r e l a t i v e l y s h o r t c y l i n d r i c a l muscle h a v i n g i t s o r i g i n on the p r o o t i q , p t e r o t i c and e x o c c i p i t a l near t h e i r meeting p o i n t and i n s e r t i n g on the medial s u r f a c e of the head of the hyomandibular. Comparison o f the cheek muscles o f M. polyacantho- cephalus and M. iaok showed no s i g n i f i c a n t d i f f e r e n c e s . Muscles o f the Opercular Apparatus o f M. polyacanthocephalus Although the o p e r c u l a r apparatus i s w e l l developed as a d e f e n s i v e mechanism, the a s s o c i a t e d musculature i s q u i t e simple. The l a r g e s t and most h i g h l y developed muscle i s the l e v a t o r arcus p a l a t i n i which i s d i r e c t l y a s s o c i a t e d w i t h the hyomandibular and p r e o p e r c l e . (This i s d i s c u s s e d i n the p r e v i o u s s e c t i o n on cheek musculature.) J u s t behind the p o s t e r i o r border o f the l e v a t o r arcus p a l a t i n i the d i l a t o r  o p e r c u l i i s found. I t has a broad o r i g i n on the v e n t r o l a t t e r a l s u r f a c e o f the wing o f the p t e r o t i c , the f i b e r s c o u r s i n g o b l i q u e l y p o s t e r o v e n t r a l l y and c o n v e r g i n g s l i g h t l y . The f i b e r s g i v e r i s e to a tendon which passes over the a r t i c u l a t o r y process o f the hyomandibular to the o p e r c l e 5 8 and i n s e r t s on the l a t e r a l s u r f a c e o f the head o f the o p e r c l e j u s t b ehind i t s a r t i c u l a t i o n w i t h the hyomandibular. Immediately p o s t e r i a d to the d i l a t o r o p e r c u l i the adductor o p e r c u l i i s found. T h i s muscle has i t s o r i g i n . o n the v e n t r a l s u r f a c e o f the p t e r o t i c , passing, out to i n s e r t on the medial s u r f a c e o f the proximal p o r t i o n o f the o p e r c l e and the s h a f t o f the o p e r c u l a r s p i n e . The l a v a t o r o p e r c u l i occurs j u s t b e h i n d the adductor o p e r c u l i . I t i s composed of two s l i p s . The a n t e r i o r most s l i p o r i g i n a t e s on the wing o f the p t e r o t i c immediately behind the a r t i c u l a t i o n - w i t h the hyomandibular and i n s e r t s on the dorsomedial s u r f a c e o f the o p e r c l e and s h a f t o f the o p e r c u l a r s p i n e . The second s l i p o r i g i n a t e s on the l a t e r a l edge of the posttemporal and i n s e r t s s i m i l a r i l y on the dorsomedial s u r f a c e o f the o p e r c l e and s h a f t o f the o p e r c u l a r s p i n e . Comparison o f Muscles of the O p e r c u l a r Apparatus o f  M. polyacanthocephalus and M. Iaok The o p e r c u l a r muscles of M. Iaok correspond to those o f M. polyacanthocephalus, e x c e p t i n g o n l y t h a t they appear to be s l i g h t l y l e s s w e l l developed on the average i n M. iaok than i n M. polyacanthocephalus. 59 F i g u r e 14: S u p e r f i c i a l Muscles o f the Cheek Region o f M. polyacanthocephalus. F i g u r e 15: S u p e r f i c i a l Muscles o f the Cheek Region o f M„ polyacanthocephalus w i t h S u b o r b i t a l S e r i e s Removed. 60 F i g u r e 16: Deep Muscles o f the Cheek Region o f M. polyacanthocephalus. F i g u r e 17: Deep Muscles o f the Cheek Region o f M. polyacanthocephalus ( S u p e r f i c i a l S l i p s o f Adductor M a n d i b u l i Removed). 61 F i g u r e 18: Muscles o f the Cheek Region o f M. po1vacanthocephalus (Adductor M a n d i b u l i Complex and Levator Arcus P a l a t i n i Removed). F i g u r e 19: Muscles o f the Opercular Apparatus o f M. polyacanthocephalus (Operculum Removed). Muscles o f the V e n t r a l Surface o f the Head o f M. polyacanthocephalus . Upon removal o f the s k i n from the r e g i o n - o f the lower jaw, the v e n t r a l muscles can be seen (Figures 20 and 21). The most prominent muscle o f t h i s area i s the geniohyoideus. I t o r i g i n a t e s on the v e n t r o l a t e r a l margin o f the proximal p o r t i o n o f the c e r a t o h y a l , courses forward and s l i g h t l y inward to i n s e r t on the medial s u r f a c e o f the d i s t a l end o f the dentary near the symphysis. T h i s muscle appears to be composed o f three d i s t i n c t b l o c k s which l i e i n an a n t e r i o r - p o s t e r i o r s e r i e s . A t the p o s t e r i o r border o f the a n t e r i o r most muscle b l o c k the muscle b i f u r c a t e s i n the h o r i z o n t a l plane sending o f f two s l i p s . One passes over and one under the i n t e r m a n d i b u l a r i s to i n s e r t on the dentary. A t the a n t e r i o r end o f the geniohyoideus, and p a r t i a l l y covered by i t , i s ' found the i n t e r m a n d i b u l a r i s muscle. T h i s muscle i s t h i n . a n d broad j o i n t l y o r i g i n a t i n g and i n s e r t i n g on the mid medial s u r f a c e s o f the d i s t a l p o r t i o n s • o f the two dentary bones. I t courses between the d o r s a l and v e n t r a l s l i p s o f the geniohyoideus muscles. The hyohvoideus muscle occurs j u s t mediad to. the p o s t e r i o r p o r t i o n o f the geniohyoideus muscles. I t i s a broad f l a t muscle which oc c u p i e s the whole b r a n c h e o s t e g a l membrane ar e a . V e n t r a l l y t h i s muscle has i t s o r i g i n on the f a c i a o f the v e n t r a l mid l i n e . From i t s o r i g i n i t courses out l a t e r a l l y to i n s e r t . o n the medial ( v e n t r a l ) edge o f the 63 f i r s t branchesostegal r a y . There are a l s o s i x d o r s a l p o r t i o n s o f t h i s muscle, the v e n t r a l f i v e o f which o r i g i n a t e and i n s e r t between adj a c e n t b r a n c h e o s t e g a l r a y s . The d o r s a l most p o r t i o n o r i g i n a t e s on the v e n t r a l p o r t i o n o f the median s u r f a c e o f the s h a f t o f the o p e r c u l a r spine and i n s e r t s on the d o r s a l edge o f the s i x t h b r a n c h e o s t e g a l r a y . Immediately above the geniohyoideus the l o n g f l a t hypohyoideus muscle i s found. T h i s muscle a r i s e s on the medial s u r f a c e o f the proximal end o f the f i r s t b r a n c h e o s t e g a l r a y and courses a n t e r i a d to i n s e r t on p o s t e r i o r v e n t r a l s u r f a c e o f the hypohyal. Medi a l to the hypohyoideus and extending f u r t h e r p o s t e r i o r l y the l a r g e urohvoideus muscle i s found. I t a r i s e s from the v e n t r o -l a t e r a l p o r t i o n o f the c l e i t h r u m runs d i r e c t l y a n t e r i a d and i n s e r t s on the a n t e r o l a t e r a l s u r f a c e o f the u r o h y a l . T h i s muscle i s composed o f three d i s t i n c t b l o c k s . The muscles o f the v e n t r a l s u r f a c e of the head were found to be i d e n t i c a l i n M„ polyacanthocephalus and M. iaok. Caudal Anatomy There appears to have been a g e n e r a l t r e n d w i t h i n the t e l e o s t e a n f i s h e s toward a f u s i o n o f p a r t s i n the caudal s k e l e t o n . T h i s i s e s p e c i a l l y e v i d e n t i n the h y p u r a l elements. T h i s t r e n d a p p a r e n t l y has o c c u r r e d independently i n s e v e r a l I N T E R M A N D I B U L A R I S G E N I O H Y O I D E U S U R O H Y O I O E U S Figure 20: S u p e r f i c i a l Muscles of the Ventral Surface of the Head of M. polyacanthocephalus. I N T E R M A N D I B U L A R lS H Y P O H Y O I D E U S U R O H Y O I D E U S Figure 21: Deep Muscles of the Ventral Surface of the Head of M. polyacanthocephalus. l i n e a g e s b ut n e v e r t h e l e s s the same end p o i n t has been a t t a i n e d though the e v o l u t i o n routes are somewhat d i f f e r e n t ( G o s l i n e , 1960, 1961). In the lower t e l e o s t s as e x e m p l i f i e d by Esox l u c i u s . (order I s o s p o n d y l i ) there are seven d i s t i n c t h y p u r a l elements. In the o r d e r Percomorphi i . e . Perca f l a v e s c e n s , there are o n l y f i v e h y p u r a l s , 2 and 3 b e i n g completely f u s e d . In the h i g h e r forms', i . e . o r d e r S c l e r o p a r e i f a m i l y C o t t i d a e , f u s i o n o f the h y p u r a l elements has been complete o r almost so. No member o f the f a m i l y has more than two h y p u r a l elements and u s u a l l y o n l y one.. i The a s s o c i a t e d caudal musculature has remained I unchanged. The o n l y major change e x h i b i t e d by the C o t t i d a e over the lower t e l e o s t s i s the apparent l o s s o f a d e f i n i t e D e l t o i d F l e x o r Tendon. The oth e r changes are those o f s m a l l divergences i n shape and e x t e n t o f the v a r i o u s muscles. Caudal S k e l e t o n o f M. polyacanthocephalus The caudal s k e l e t o n i n M. polyacanthocephalus (Figure 22) e x h i b i t s almost complete f u s i o n o f the u r o s t y l e and h y p u r a l elements. Only a s m a l l gap remains a t the d i s t a l end o f t h i s complex, s e r v i n g to d i v i d e the h y p u r a l r e g i o n i n t o two more o r l e s s d i s t i n c t p l a t e s . The f i r s t ( d o r s a l most) p l a t e serves to support the s i x d o r s a l 66 caudal rays (five branched rays and a dorsal most unbranched ray) and the second (ventral most) the ventral six (four branched rays and two ventral unbranched rays). Three well defined epiurals are present and together with the modified neural spine of the ultimate vertebra, support the dorsal caudal f i n r a y l e t s . The ventral caudal f i n raylets are wholly supported by the much modified haemal spine of the ultimate vertebra. The neural spines of the ultimate and penultimate vertebrae are broad and f l a t ; that of the ultimate vertebra i s almost square i n shape, and that of the penultimate has a shorter base and approximating a rectangle or i n some instances a t r i a n g l e . The haemal spine of the ultimate vertebra i s greatly broadened at i t s base and extends obliquely posteriad to a point opposite the posteroventral edge of the second hypural plate. The haemal spine of the penultimate vertebra i s s i m i l a r i n form to the neural spine. The neural and haemal spines of the antipenultimate vertebra also exhibit some modification and are si m i l a r i n form to those of the penultimate vertebra. The number of posterior vertebrae which have under-gone modification of t h e i r neural and haemal spines i s variab l e . Usually only the l a s t four are modified, but as many as the l a s t s i x may exhi b i t some broadening of the spines. 67 S t a r t i n g a t the s i x t h v e r t e b r a a n t e r i o r to the h y p u r a l r e g i o n there i s a gradual l a t e r a l expansion o f the v e r t e b r a l b o dies p o s t e r i a d and thus the centrum becomes e l i p t i c a l i n c r o s s - s e c t i o n . Comparison;of the Caudal Skeleton o f  M. polyacanthocephalus and M. jaok In most r e s p e c t s the c a u d a l s k e l e t o n of M. jaok i s m o r p h o l o g i c a l l y s i m i l a r to t h a t o f M. polyacanthocephalus. There are s e v e r a l d i f f e r e n c e s which are o f a minor nature. In M. iaok the f i r s t h y p u r a l p l a t e supports s i x rays which are comprised o f 4-5 branched rays and 1-2 unbranched. rays thus e x h i b i t i n g a g r e a t e r v a r i a b i l i t y than M. polyacantho-cephalus which has o n l y 5 branched rays and 1 unbranched ray on the f i r s t p l a t e . There i s a l s o a s l i g h t l y g r e a t e r range i n the number o f caudal v e r t e b r a e on which the n e u r a l and haemal spines are a t a l l m o d i f i e d ; M. jaok h a v i n g a range o f 4-8 and M. polyacanthocephalus a range o f 4-6. L a s t l y , i n M. jaok the n e u r a l and haemal spines ( i n a t l e a s t the l a s t four v e r t e b r a e ) are p r o p o r t i o n a t e l y somewhat s h o r t e r than those o f M. polyacanthocephalus. 68 The Muscles o f trie Caudal F i n o f M. polyacanthocephalus Upon removal o f the s k i n and u n d e r l y i n g tough c o n n e c t i v e t i s s u e and f a s c i a l a y e r s from the c a u d a l r e g i o n , the s u p e r f i c i a l musculature i s r e v e a l e d . The caudal musculature i s g e n e r a l l y d i v i d e d i n t o d o r s a l and v e n t r a l s e c t i o n s by the transverse.myoseptum. S u p e r f i c i a l Caudal Musculature S u p e r f i c i a l D o r s a l F l e x o r Muscle (Figure 2 6) The S u p e r f i c i a l D o r s a l F l e x o r Muscle i s a broad f l a t muscle composed of two bundles. Tne d o r s a l bundle o f the muscle i n s e r t s by means o f tendon s l i p s on the p o s t e r i o r f i v e c a u d a l f i n r a y l e t s and ray D l . The v e n t r a l p o r t i o n sends put tendon s l i p s wnich i n s e r t on the cau d a l f i n rays D1-D4. Both d o r s a l and v e n t r a l bundles o f the s u p e r f i c i a l d o r s a l f l e x o r muscle r e p r e s e n t s tne m o d i f i c a t i o n o f the l a s t e p a x i a l myomere. A broad tendon a r i s i n g from the v e n t r a l p o r t i o n o f the e p a x i a l myosepta runs back, p a r a l l e l to tne lower edge o f the v e n t r a l p o r t i o n o f the s u p e r f i c i a l d o r s a l f l e x o r muscle and the t r a n s v e r s e myoseptum and i n s e r t s on c a u d a l rays D4-D6. S u p e r f i c i a l V e n t r a l F l e x o r Muscle (Figure 26) V e n t r a l l y and running; p a r a l l e l to the t r a n s v e r s e myoseptum, i s the S u p e r f i c i a l V e n t r a l F l e x o r Muscle. The muscle i s composed o f two p o r t i o n s , a d o r s a l and a v e n t r a l 69 p o r t i o n . Tne d o r s a l p o r t i o n o f t h i s muscle i s s h o r t and broad g i v i n g o f f tendon s l i p s which i n s e r t on theheads o f caudal f i n rays V1-V6. The v e n t r a l p o r t i o n i s narrow and elongate, terminating, p o s t e r i o r l y i n tendon s l i p s which i n s e r t on the heads o f the l a s t 4 v e n t r a l caudal f i n r a y l e t s and r a y VI. R e f l e c t i o n o f the s u p e r f i c i a l v e n t r a l f l e x o r exposed a broad f l a t tendon which o r i g i n a t e s from the d o r s a l p o r t i o n s o f the p o s t e r i o r h y p a x i a l myosepta and runs back to i n s e r t on the head of the c a u d a l rays V3-V6. Deep Caudal Musculature Hypochordal L o n g i t u d i n a l Muscle (Figure 23) The hypochordal l o n g i t u d i n a l muscle i s almost t r i a n g u l a r i n o u t l i n e . I t o r i g i n a t e s from the second h y p u r a l p l a t e , passes up beneath the deep v e n t r a l f l e x o r muscle and over the v e n t r a l p o r t i o n o f tne s u p e r f i c i a l d o r s a l f l e x o r g i v i n g o f f three tendonous s l i p s which i n s e r t on the heads of caudal f i n rays D1-D3. Deep D o r s a l F l e x o r Muscle (Fi g u r e s 24 and 25) Immediately below the s u p e r f i c i a l d o r s a l f l e x o r the deep d o r s a l f l e x o r muscle i s seen. T h i s muscle i s composed of d o r s a l and v e n t r a l p o r t i o n s . The d o r s a l p o r t i o n o r i g i n a t e s on the n e u r a l spines of the u l t i m a t e and penultimate v e r t e b r a e and on e p i u r a l s 70 1 and 2. Tendon s l i p s are giv e n o f f p o s t e r i o - d o r s a l l y and i n s e r t on the p o s t e r i o r most 5 d o r s a l r a y l e t s . The v e n t r a l ; p o r t i o n o r i g i n a t e s on the n e u r a l spine o f the pe n u l t i m a t e v e r t e b r a and on the b o d i e s and n e u r a l spines o f the antepenultimate v e r t e b r a and the one immediately preeeeding i t . T h i s p o r t i o n g i v e s r i s e t o tendon s l i p s which i n s e r t on caudal f i n r a y s D1-D6. Deep V e n t r a l F l e x o r Muscle (Figures 24 and 25) The deep v e n t r a l f l e x o r muscle l i e s immediately beneath the s u p e r f i c i a l v e n t r a l f l e x o r . I t is:composed o f th r e e p o r t i o n s : s u p e r f i c i a l , d o r s a l , and v e n t r a l . The s u p e r f i c i a l p o r t i o n o f t h i s muscle o v e r l i e s some o f the d o r s a l and v e n t r a l p o r t i o n s , i t s f i b e r s c o u r s i n g o b l i q u e l y . I t o r i g i n a t e s on the. hemal. s p i n e s o f the u l t i m a t e and pe n u l t i m a t e v e r t e b r a e , the hemal sp i n e and body o f the antepenultimate v e r t e b r a , and the body o f the v e r t e b r a immediately a n t e r i a d . T h i s p o r t i o n y i e l d s two f a i r l y broad tendon s l i p s which i n s e r t on the heads.of caudal rays V5 and V6. The d o r s a l p o r t i o n o r i g i n a t e s on the head o f the h y p u r a l p l a t e , the body and hemal sp i n e o f the u l t i m a t e v e r t e b r a , and the body o f the pe n u l t i m a t e v e r t e b r a . I t i n s e r t s by way o f tendon s l i p s on the v e n t r a l caudal f i n rays V1-V6. The v e n t r a l p o r t i o n o r i g i n a t e s on t h e hemal spines o f the u l t i m a t e and pen u l t i m a t e v e r t e b r a e . I t g i v e s o f f 71 t e n d o n s l i p s and i n s e r t s on t h e p o s t e r i o r most 5 v e n t r a l r a y l e t s . P r o f u n d a l C a u d a l M u s c u l a t u r e  I n t e r r a d i a l M u s c l e s ( F i g u r e 2 6 ) The i n t e r r a d i a l m u s c l e s a r e w h o l l y r e s t r i c t e d t o t h e c a u d a l f i n and do n o t h a v e any c o n n e c t i o n w i t h t h e v e r t e b r a l c o l u m n . T h e s e m u s c l e s a r e f o u n d o n l y on t h e 6 d o r s a l and 6 v e n t r a l c a u d a l r a y s and a r e composed o f o n l y one p o r t i o n . The m u s c l e s o r i g i n a t e on t h e h e a d s o f t h e r a y s . The o r i g i n o f a g i v e n i n t e r r a d i a l m u s c l e may b e on one, two o r t h r e e d i f f e r e n t r a y s . T h e y i n s e r t , i n t h e c a s e o f t h e d o r s a l I n t e r r a d i a l s ( t h o s e m u s c l e s i n s e r t i n g on t h e d o r s a l r a y s ) on t h e v e n t r o - l a t e r a l m a r g i n s o f t h e r a y s and i n t h e c a s e o f t h e v e n t r a l i n t e r r a d i a l s ( t h o s e m u s c l e s i n s e r t i n g on t h e v e n t r a l r a y s ) on t h e d o r s o - l a t e r a l m a r g i n s . The I n t e r r a d i a l M u s c l e s o r i g i n a t e and i n s e r t as f o l l o w i n g : ORIGIN INSERTION D 2 , 3 , 4 ; D I D 4 , 5 D 2 D 5 , 6 D 3 D 6 , V 6 D 4 V 6 D 5 V 6 D 6 D 6 V 6 D 6 V 5 V 6 , D 6 V 4 V 5 , 6 V 3 V 3 , 4 , 5 V 2 V 2 , 3 V I I n t e r r a d i a l m u s c l e s i n s e r t i n g on r a y s D 4 , D 5 , and D 6 e x t e n d o v e r t h o s e m u s c l e s o r i g i n a t i n g f r o m r a y D 6 , f r o m t h e i r o r i g i n on t h e h e a d o f r a y V 6 . DORSAL RAYLETS Figure 22: The Caudal Skeleton of M. polyacanthocephalus. Figure 23: The Posi t i o n of the Hypochordal Longitudinal Muscle of M... polyacanthocephalus. 73 Figure 2 4 : The Deep Caudal Musculature of M. polyacanthocephalus. Figure 2 5 s The Deep Caudal Musculature of M. polyacanthocephalus , showirig S u p e r f i c i a l Bundle of Deep Ventral Flexor. 74 Figure 26: The S u p e r f i c i a l Caudal Musculature of M. polyacanthocephalus. 7 5 Comparison o f Caudal Musculature o f  M. polyacanthocephalus and M. jaok The caudal musculature o f M. jaok i s v e r y s i m i l a r as t h a t o f M. polyacanthocephalus. Minute d i f f e r e n c e s i n the e x t e n t o f the o r i g i n s o f c e r t a i n o f the muscles were encountered b u t these were found to be w e l l w i t h i n the range o f v a r i a t i o n between i n d i v i d u a l s o f M. polyacanthocephalus examined. S t r u c t u r e o f B r a n c h i a l Apparatus o f M. polyacanthocephalus The b r a n c h i a l apparatus o f M. polyacanthocephalus (Figure 27) i s composed o f f o u r g i l l arches and a s m a l l pseudbbranch o p p o s i t e the medial s u r f a c e o f the hyomandibular. There i s no s l i t or pore behind the l a s t g i l l a r c h . A s e r i e s o f round or o v a l shaped g i l l r a k e r s a r i s e from the medial and l a t e r a l s u r f a c e s o f the f i r s t t h r e e g i l l arches and from the l a t e r a l s u r f a c e o f the f o u r t h . The m a j o r i t y o f the g i l l r a k e r s occur on the ceratobraCchial r e g i o n w i t h o n l y the o c c a s i o n a l one on the d i s t a l end o f the e p i b r a n c h i a l r e g i o n . The g i l l r a k e r s are u s u a l l y almost round i n o u t l i n e w i t h t h e i r exposed s u r f a c e s b e a r i n g numerous s m a l l s p i n u l e s which r a d i a t e up and out. There i s u s u a l l y a s m a l l b a s a l p o r t i o n which i s b u r i e d i n the t i s s u e and i s nonspinate. The r a k e r s o f the l a t e r a l s u r f a c e o f the f i r s t g i l l arch are u s u a l l y f l a t whereas those o f the o t h e r s are n o t i c e a b l y 76 more obtuse. O c c a s i o n a l l y some o f the more a n t e r i o r g i l l r a k e r s o f the l a t e r a l s u r f a c e o f the f i r s t g i l l arch become fused i n p a i r s . The g i l l r a k e r s of the medial s u r f a c e are so p o s i t i o n e d as to more or l e s s i n t e r l o c k w i t h those o f the l a t e r a l s u r f a c e o f the f o l l o w i n g g i l l a r c h . Comparison o f the B r a n c h i a l Apparatus o f  M. polyacanthocephalus and M. jaok The number and s t r u c t u r e o f the g i l l arches a r e i d e n t i c a l i n bot h s p e c i e s . The g i l l r a k e r s are a l s o s i m i l a r , b u t the s p i n u l e s on the g i l l r a k e r s o f M. jaok are s l i g h t l y s t r o n g e r , l o n g e r and l e s s numerous than those o f M. polyacanthocepahlus. The shape o f the g i l l r a k e r s o t h e r than those o f the l a t e r a l s u r f a c e o f the f i r s t arch are more dome-shaped i n p r o f i l e and i n some i n s t a n c e s almost s p h e r o i d i n M. jaok. The Morphology o f the O l f a c t o r y Rosette  o f M. polyacanthocephalus The o l f a c t o r y r o s e t t e o f M. polyacanthocephalus l i e s below and j u s t l a t e r a l l y from the a n t e r o l a t e r a l p o r t i o n o f the l a t e r a l p r o j e c t i o n o f the n a s a l bone, immediately beneath the a n t e r i o r n o s t r i l . I t i s more or l e s s round 77 78 i n shape b u t f l a t i n p r o f i l e and i s composed o f 12-16 elongate f l a p - l i k e l a m e l l a e . For d e t a i l s o f morphology see F i g u r e 28. Comparison o f the Morphology o f the O l f a c t o r y  Rosettes o f M. polyacanthocephalus and M. iaok The morphology o f the o l f a c t o r y r o s e t t e o f M. jaok i s almost i d e n t i c a l t o t h a t o f M. polyacanthocephalus (Figures 28 and 29). The number o f l a m e l l a e tend to be s l i g h t l y h i g h e r (14-16) i n M. jaok. In M. jaok t h e r e are u s u a l l y a few s c a t t e r e d melanophores on the s u r f a c e o f the r o s e t t e and on the l i n i n g o f the o l f a c t o r y chamber which are not a predominant f e a t u r e i n M. p olyacanthocephalus . The c e n t r a l o r i g i n o f the l a m e l l a e appear to be s l i g h t l y d i f f e r e n t i n the two s p e c i e s . In M. polyacanthocephalus they appear to o r i g i n a t e from an elongate r i d g e o f t i s s u e whereas i n those o f M. iaok t h e i r o r i g i n s are more c e n t r a l i z e d and l e s s spread out. E l e c t r o p h o r e s i s o f Muscle P r o t e i n An e x c e l l e n t review o f the p h i l o s o p h y u n d e r l y i n g the a p p l i c a t i o n o f p r o t e i n s t u d i e s to phylogeny has been pr e s e n t e d b y S i b l e y (1960). I n v e s t i g a t i o n s o f v a r i o u s p r o t e i n s o f amphibians and r e p t i l e s by Dessauer and Fox F i g u r e 28: The O l f a c t o r y Rosette o f M. polyacanthocephalus. F i g u r e 29: The O l f a c t o r y Rosette o f M. 1aok. 80 (1956), b i r d s by S i b l e y (1960), and f i s h e s by Tsuyuki e t a l , (1965a, b) have i n g e n e r a l s u b s t a n t i a t e d c l a s s i f i c a t i o n s developed on the b a s i s o f morphology. In the p r e s e n t study no attempt was made to perform exhaustive examination o f the p r o t e i n s o f the two s p e c i e s . However i t was b e l i e v e d d e s i r a b l e t o undertake some p r e l i m i n a r y i n v e s t i g a t i o n s o f the muscle myogens t o determine whether t h e r e were important d i f f e r e n c e s . The r e s u l t s o f t h i s p r e l i m i n a r y e x p l o r a t i o n w i l l serve as a guide to f u t u r e work t h a t i s planned to cover the e n t i r e genus. The analyses o f the f o u r samples from each s p e c i e s r e v e a l e d c o n s i s t a n t d i f f e r e n c e s (Figure 30). M.„ polyacantho-cephalus showed a pronounced c a t h o d i c band t h a t was absent i n M. jaok. At the same time, the f i r s t anodic band, one o f the most p r o m i n e n t l y d i s p l a y e d by M. jaok was. absent i n M. polyacanthocephalus. There are o t h e r l e s s obvious d i f f e r e n c e s i n the anodic p a t t e r n . Figure 30. Starch-gel Electropherograms of the Muscle Proteins of: A. M. polyacanthocephalus and B. M. jaok. (Cathode to Left, Anode to Right) 82 Comparison of M e r i s t i c C h a r a c t e r s o f  M. polyacanthocephalus and M. jaok I t i s g e n e r a l l y found t h a t M. jaok e x h i b i t s l e s s m e r i s t i c v a r i a t i o n than does M. polyacanthocephalus (Table 1) „ In the spinous d o r s a l f i n , t h a t o f polyacanthocephalus v a r i e s from 8 to 10 spines , 10 b e i n g the predominant number. In M. jaok the number of spines s i m i l a r i l y v a r i e s from 8 to 10 however 9 spines predominate (Figure 31) . The number of rays i n the s o f t d o r s a l f i n (Figure 32) ranges from 10 to 15 i n M. polyacanthocephalus, 14 b e i n g the most common. In M. jaok there i s much l e s s v a r i a t i o n e x h i b i t e d i n the number o f rays, t h e i r numbers ran g i n g from 14 to 16, w i t h 15 b e i n g the most common. The number o f branched c a u d a l rays i s about the same f o r both s p e c i e s . They v a r y i n number from 7 to 11, w i t h 9 u s u a l l y predominating. The most pronounced m e r i s t i c d i f f e r e n c e i s found i n the number o f a n a l f i n rays (Figure 33), In M„ polyacanthocephalus the number v a r i e s from 8 to 15, the . mean and a l s o most predominant number b e i n g 12, The v a r i a t i o n e x h i b i t e d by M. jaok i s c o n s i d e r a b l e l e s s , the number ranging from 12 to 15. The mean number o f rays i s 13.5 w i t h 13 and 14 b e i n g e q u a l l y f r e q u e n t . The number of p e c t o r a l f i n r a y s . i s s i m i l a r i n both s p e c i e s , v a r y i n g from 17 to 19 w i t h 18 b e i n g the more 83 common. In one i n s t a n c e M. jaok i s recor d e d to have one of the p e c t o r a l f i n s w i t h o n l y 16 r a y s . The occurence o f unequal numbers of rays between the two p e c t o r a l f i n s i s common. I t occurs i n about 13% o f the 63 specimens o f M. polyacanthocephalus and i n about 15% o f the 102 specimens o f M. jaok examined. The number o f p e l v i c s p i n e s and rays i n both s p e c i e s are a b s o l u t e l y c o n s t a n t a t 1-3. The v e r t e b r a l number e x h i b i t s more v a r i a t i o n . i n M. polyacanthocephalus than i t does i n M. jaok (Figure 34). In the former s p e c i e s the number v a r i e s from 35 to 3 7, the mean number b e i n g 35.5 and 35 the most common s i t u a t i o n . In the l a t t e r s p e c i e s , the number ranges from 35 to 36, the mean b e i n g 35.1 and 35 most predominant number. The l a t e r a l l i n e o s s i c l e numbers are f a i r l y v a r i a b l e i n both s p e c i e s (Figure 35). Those o f M„ jaok have a s l i g h t l y g r e a t e r v a r i a b i l i t y than those o f M. polyacanthocephalus. The number o f o s s i c l e s ranges from 39 to 45 i n M. polyacanthocephalus w i t h a mean number of 41.5 and from 38 to 45 w i t h a mean number o f 41.7 i n M. jaok, A most pronounced d i f f e r e n c e i s found i n the number o f the l o n g e s t p e c t o r a l f i n r a y (Figure 36)„ In M. polyacanthocephalus the number ranges from 4-8, 6 b e i n g the most common. In M. jaok there i s s l i g h t l y l e s s v a r i a t i o n the number ra n g i n g from 2-5 w i t h 3 b e i n g the most common. The number of the l o n g e s t p e l v i c f i n r a y i s 84 s i m i l a r i n both s p e c i e s (Figure 37), however there i s a l i t t l e more v a r i a t i o n e x h i b i t e d by M. polyacanthocephalus than by M. j a o k . In M. polyacanthocephalus the number v a r i e s from 1-3 w i t h 2 predominating. In M. jaok the range i s from 2-3 w i t h both 2 and 3 b e i n g e q u a l l y predominant. The number of the l o n g e s t c a u d a l f i n r a y e x h i b i t s a pronounced d i f f e r e n c e between the two s p e c i e s (Figure 38). In Mj. polyacanthocephalus the number ranges from 3-9, the mean b e i n g 7.32 and 8 the most common. M„ jaok e x h i b i t s much l e s s v a r i a t i o n , the number r a n g i n g from 1-3, the mean b e i n g 1.03 and 1 the most predominant. The number of the l o n g e s t f i r s t , d o r s a l f i n spine (Figure 39) i n M. polyacanthocephalus v a r i e s from 3-5, the mean 4.31 and 4 the most common number. In M. iaok the range i s s i m i l a r i l y 3-5 and 4 the most common, however the mean i s somewhat lower a t 3.73. The number o f the l o n g e s t second d o r s a l f i n r ay (Figure 40) i n M„ polyacanthocephalus v a r i e s from 3-5 w i t h 4 b e i n g the most, predominant and a mean o f 4.16. The range of v a r i a b i l i t y e x h i b i t e d by M. jaok i s much g r e a t e r , r a n g i n g from 3-7 the mean b e i n g 4.35 and 4 s i m i l a r i l y predominating. In M. polyacanthocephalus the number o f the l o n g e s t a n a l f i n ray (Figure 41) ranges from 5-8, the mean b e i n g 6.95 and w i t h 6 predominating. M„ jaok a g a i n e x h i b i t s more v a r i a b i l i t y h a v i ng a range from 5-9 w i t h a mean o f 7.0 7 and w i t h 7 the most predominant, number. Table; i . M e r i s t i c Comparison of M„ polyacanthocephalus and M. jaok. M. polyacanthocephalus M. jaok range mode range mode 1st D o r s a l Spines 8-10 10 8-10 9 2nd D o r s a l Rays 10-15 14 14-16 15 Ana l Rays 8-15 12 12-15 13-14 P e c t o r a l F i n Rays 17-19 18 16-19 18 V e r t e b r a l Number 35-37 35 35-36 35 L a t e r a l L i n e O s s i c l e s 39-45 41 38-45 42 Longest P e c t o r a l Ray 4-8 6 2-5 3 Longest P e l v i c Ray 1-3 2 2.-3 2-3 Longest Caudal Ray 3-9 8 1-3 1 Longest 1 s t D o r s a l Spine 3-5 4 3-5 4 Longest 2nd D o r s a l Ray 3-5 4 3-5 4 Longest A n a l Ray 5-8 6 5-9 7 F i g u r e 31: Comparison o f V a r i a t i o n i n Spine Number of 1 s t D o r s a l F i n i n M. polyacanthocephalus and M. jaok. F i g u r e 32: Comparison o f V a r i a t i o n i n Number of Rays of 2nd D o r s a l F i n i n M. polyacanthocephalus and M. jaok. F i g u r e 33: Comparison of V a r i a t i o n i n Number of A n a l F i n Rays i n M. polyacanthocephalus and M. jaok. F i g u r e 34: Comparison o f V a r i a t i o n i n V e r t e b r a l Number i n M. polyacanthocephalus and M. jaok. M. HOLY AC ANTHOCEFH ALUS t 10 M. POLYACANTHOCEPHALUS r t i _ i i i i i i i i M. JAOK 9 10 11 12 13 14 15 16 M. PCLYAC ANTHOCEPHALUS M. JAOK I I I I 1 I L_ 8 9 10 11 12 13 14 15 F i g u r e 35: Comparison of V a r i a t i o n i n L a t e r a l L i n e Pore Number i n M. polyacanthocephalus and M. ia o k . F i g u r e 36: Comparison o f V a r i a t i o n i n the Number o f the Longest P e c t o r a l F i n Ray i n M. polyacanthocephalus and M. iaok. F i g u r e 37: Comparison o f V a r i a t i o n i n the Number of the Longest P e l v i c F i n Ray i n M. polyacanthocephalus and M. jaok. F i g u r e 38: Comparison o f V a r i a t i o n i n the Number of the Longest Caudal Ray i n M. polyacanthocephalus and M. jaok. F i g u r e 39: Comparison of V a r i a t i o n i n the Number o f the Longest 1st D o r s a l Spine i n M. polyacanthocephalus and M. ia o k . F i g u r e 40: Comparison of V a r i a t i o n i n the Number o f the Longest 2nd D o r s a l Ray i n M„ polyacanthocephalus and M. jaok. F i g u r e 41: Comparison of V a r i a t i o n i n . t h e Number o f the Longest A n a l Ray i n M„ polyacanthocephalus and M. jaok. 89 C o m p a r i s o n o f M o r p h e m e t r i e a n d Age R e l a t e d Measurements  o f M. p o l y a c a n t h o c e p h a l u s a n d M. i a o k F o r t h e c o m p a r i s o n o f morphometry t h e 32 m easure-ments t a k e n were e a c h t r a n s f o r m e d t o a p e r c e n t a g e o f e a c h o t h e r measurement t h u s y i e l d i n g 992 d i f f e r e n t c o m b i n a t i o n s on w h i c h t o b a s e t h e c o m p a r i s o n . From t h e r e s u l t i n g c o m p a r i s o n s i t was f o u n d t h a t o n l y d e p t h o f c a u d a l p e d u n c l e a g a i n s t l e n g t h o f a n a l f i n b a s e a n d d e p t h o f c a u d a l p e d u n c l e a g a i n s t l e n g t h o f s e c o n d d o r s a l f i n b a s e d i f f e r e d t o a n y e x t e n t b e t w e e n t h e two s p e c i e s ( F i g u r e s 42 a n d 43)„ V a r i a t i o n was c o n s i d e r a b l e i n b o t h s p e c i e s b u t e s p e c i a l l y i n M. p o l y a c a n t h o c e p h a l u s . I n g e n e r a l i t c a n be s a i d t h a t M. p o l y a c a n t h o c e p h a l u s i s a somewhat more r o b u s t s p e c i e s t h a n M, j a o k . The h e a d and e y e s a r e a l s o somewhat l a r g e r . The s p i n o u s a n d s o f t d o r s a l f i n s a n d t h e p e l v i c f i n s a r e , o n t h e a v e r a g e , s l i g h t l y more p o s t e r i o r i n M, p o l y a c a n t h o c e p h a l u s . F i g u r e s 42 a n d 43 r e v e a l t h a t g r o w t h i s h e t e r o g o n i c i n b o t h s p e c i e s a n d t h a t t h e r a t e o f g r o w th o f t h e s e b o d y p a r t s a r e more r a p i d i n M„ p o l y a c a n t h o c e p h a l u s t h a n i n M. j a o k . T h i s i s a l s o t r u e o f most o f t h e b o d y p a r t s i n r e l a t i o n t o s t a n d a r d l e n g t h . F i g u r e 42: Comparison of the R e l a t i o n of Depth a t Caudal Peduncle w i t h Length o f A n a l F i n Base i n M. polyacanthocephalus and M„ iaok. F i g u r e 43: Comparison of the R e l a t i o n o f Depth a t Caudal Peduncle w i t h Length of Second D o r s a l F i n Base i n M. polyacanthocephalus and and M. jaok. E t £ 30f 111 25 u z Q UJ 20 < Q < u li. o Q. Lu a 15 10 5 o o o o 0 ° ° o o 0 °. o o • o 0 O t o ( u # . o o O M . P O L Y A C A N T H O C E P H A L U S • M . J A O K 10 20 30 40 50 60 70 80 L E N G T H O F A N A L F I N B A S E (mm.) 90 100 E £ 30 U l _I u z a UJ a. < a < u LL o 0. U l a 25 20 15 10 5r O O A •• • °o° 3 • • M . P O L Y A C A N T H O C E P H A L U S M . J A O K 0 20 40 60 80 100 120 L E N G T H O F S E C O N D D O R S A L FIN B A S E (mm.) 91 Ecology and L i f e H i s t o r y o f M. polyacanthocephalus Very l i t t l e i s known about the ecology and l i f e h i s t o r y of M. polyacanthocephalus. From the specimens examined i t was not p o s s i b l e to estimate the time o f spawning, or whether the l a r v a e and p o s t l a r v a e are p e l a g i c . Some o f the p o s t l a r v a e and the j u v e n i l e s appear to p r e f e r the i n t e r t i d a l and h i g h s u b t i d a l zones. They u s u a l l y i n h a b i t the more rocky t i d e p o o l s , i n t e r t i d a l and h i g h s u b t i d a l areas where algae are abundant and o f t e n where there i s a heavy surge. They are a l s o r e c o r d e d from sandy areas where e e l grass and Ulva are abundant. The a d u l t s u s u a l l y i n h a b i t deeper water, i n areas w i t h predominantly h a r d or rocky bottoms. They appear to f e e d mainly on s m a l l f i s h and c r u s t a c e a n s . Ecology and L i f e H i s t o r y o f M. iaok S i m i l a r to M. polyacanthocephalus almost n o t h i n g i s known about the ecology and l i f e h i s t o r y o f M. jaok. In a c o l l e c t i o n from the western B e r i n g Sea, which was taken i n e a r l y J u l y , two l a r g e females were found to have a few l a r g e , but mostly s m a l l eggs i n t h e i r o v a r i e s . The l a r g e eggs were about two m i l l i m e t e r s . i n diameter and the s m a l l ones about h a l f a m i l l i m e t e r . T h i s would suggest t h a t they had spawned j u s t p r e v i o u s l y . Nothing i s known about the 9 2 l a r v a e and p o s t l a r v a e however because a l l the s m a l l specimens were t a k e n i n the h i g h s u b t i d a l zone i t may be v a l i d t o assume t h a t t h e y f r e q u e n t t h i s zone. As f o r M. p o l y a c a n t h o c e p h a l u s , the a d u l t s a r e found m a i n l y i n a r e a s w i t h p r e d o m i n a n t l y h a r d o r r o c k y bottoms. They a r e r e c o r d e d a l s o from sand and mud a r e a s w i t h e e l g r a s s beds and o c c a s i o n a l s m a l l r o c k y outcroppings„ T h e i r f o o d appears t o c o n s i s t m a i n l y o f c r u s t a c e a n s and s m a l l f i s h . G eographic D i s t r i b u t i o n o f M. p o l y a c a n t h o c e p h a l u s M. p o l y a c a n t h o c e p h a l u s o c c u r s i n marine w a t e r s from n o r t h e r n Washington, n o r t h t h r o u g h B r i t i s h Columbia and S o u t h e a s t e r n A l a s k a t o the A l a s k a n P e n i n s u l a , west a l o n g the A l a s k a n P e n i n s u l a , A l e u t i a n I s l a n d , Okhotsk Sea t o n o r t h e r n Japan. Geographic D i s t r i b u t i o n o f M. i a o k M. i a o k o c c u r s i n marine w a t e r s from Kachemak Bay, G u l f o f A l a s k a west a l o n g t h e A l e u t i a n Islands,. Okhotsk Sea to n o r t h e r n Japan and a l s o i n the B e r i n g Sea. 93 Depth D i s t r i b u t i o n of M. polyacanthocephalus Throughout i t s geographic range M. polyacanthocephalus occurs i n a wide range o f depths. I t appears t h a t the post-l a r v a e and j u v e n i l e s o f t h i s s p e c i e s show a d i s t i n c t p r e f e r e n c e f o r shallow water, o c c u r i n g abundantly i n t i d e p o o l s , i n t e r t i d a l areas, and h i g h e r s u b t i d a l r e g i o n s . The a d u l t s on the o t h e r hand, do not f r e q u e n t the shallower waters but occur almost e x c l u s i v e l y i n the s u b t i d a l zone and to depths o f a t l e a s t 250 fathoms. Depth D i s t r i b u t i o n of M. iaok There i s c o n s i d e r a b l y l e s s depth data f o r M. jaok than f o r M. polyacanthocephalus. I t appears t h a t M. j a o k has a much more r e s t r i c t e d depth d i s t r i b u t i o n than does M. polyacanthocephalus. Of the 33 c o l l e c t i o n s of M. jaok o n l y one i n d i v i d u a l was found from an i n t e r t i d a l a r e a . I t was a l s o found t h a t even w i t h the e x t e n s i v e c o l l e c t i n g i n areas o f A l a s k a where a d u l t s of both s p e c i e s and p o s t l a r v a e and j u v e n i l e s of M. polyacanthocephalus were found, the post-l a r v a e o f M. jaok were absent and o n l y a few j u v e n i l e s were found. The a d u l t s and the m a j o r i t y of the j u v e n i l e s appear to be almost e x c l u s i v e l y s u b t i d a l . They occur from the h i g h s u b t i d a l zone to depths o f 85 fathoms i n the A l e u t i a n I s l a n d s and to 200 fathoms i n two i n s t a n c e s from the B e r i n g Sea. They appear to be. most abundant between 30 and 60 fathoms. 94 DISCUSSION Every s p e c i e s o f l i v i n g organism i s a complex o f s t r u c t u r a l and f u n c t i o n a l a t t r i b u t e s t h a t i n t o t a l comprise a s u c c e s s f u l o p e r a t i n g e n t i t y . The s y s t e m a t i s t i s u s u a l l y not concerned w i t h those s t r u c t u r a l f e a t u r e s which p l a c e the animal i n i t s h i g h e r taxa. The f e a t u r e s of anatomy t h a t are used to d i s t i n g u i s h genera and s p e c i e s may have obvious importance to the s u r v i v a l of the s p e c i e s i n the environment which i t o c c u p i e s . C h a r a c t e r s o f t h i s s o r t may be i n v o l v e d i n p r o t e c t i o n from enemies, o r they may enable i n d i v i d u a l s to f i n d each o t h e r f o r mutual p r o t e c t i o n or f o r communciation which, under a p p r o p r i a t e circumstances, may l e a d to s e l e c t i o n o f a mate. A l t e r n a t i v e l y they may have no apparent f u n c t i o n a l s i g n i f i c a n c e . I t has been customary to a s s i g n those anatomical f e a t u r e s f o r which no a d a p t i v e s i g n i f i c a n c e can be assigned, to the workings o f g e n e t i c d r i f t . I d e a l l y , the s y s t e m a t i s t seeks not o n l y to p r o v i d e key c h a r a c t e r i s t i c s f o r the mere r e c o g n i t i o n o f a s p e c i e s , but a l s o s h o u l d e x p l o r e the t o t a l anatomy, p h y s i o l o g y , b i o c h e m i s t r y , e t h o l o g y and ecology o f the s p e c i e s t h a t he i s s t u d y i n g . Probably no s p e c i e s o f the worlds b i o t a has y e t been the s u b j e c t o f such an i d e a l study. T h i s p r e s e n t study o f two a p p a r e n t l y c l o s e l y s i m i l a r 95 s p e c i e s o f the c o t t i d genus Myoxocephalus has been r e s t r i c t e d l a r g e l y to anatomical c h a r a c t e r i s t i c s . Although the degree of m o r p h o l o g i c a l s i m i l a r i t y between these two s p e c i e s i s remarkable, i n g e n e r a l M. polyacanthocephalus i s a more robust s p e c i e s than i s M. jaok, however so much v a r i a t i o n i s encountered i n the morphometric measurements t h a t o n l y two of the 992 combinations examined y i e l d e d usable d i f f e r e n c e s . T h i s study has however brought to l i g h t a number o f anatomical f e a t u r e s t h a t would appear to be o f f u n c t i o n a l s i g n i f i c a n c e , p r i m a r i l y i n the important area o f s p e c i e s r e c o g n i t i o n and mate s e l e c t i o n . The most important o f these f e a t u r e s are c o l o r a t i o n and s e x u a l dimorphism i n c o l o r and a l s o i n p e c t o r a l and p e l v i c f i n s t r u c t u r e . The i n t e g r i t y o f two c l o s e l y s i m i l a r s p e c i e s i s d e c i d e d a t the time o f r e p r o d u c t i o n . I f the s p e c i e s a c c u r a t e l y i d e n t i f y mates w i t h i n t h e i r own s p e c i e s , h y b r i d i z a t i o n w i l l be r a r e or absent. Research on behaviour has r e v e a l e d t h a t c o l o r p a t t e r n , exaggerated s t r u c t u r a l d e t a i l s , and b e h a v i o u r a l c h a r a c t e r i s t i c s are f e a t u r e s u s u a l l y used i n the s e l e c t i o n o f a p p r o p r i a t e mates ( S c h i l l e r , 1957; Tinbergen, 1951). In the p r e s e n t p a i r o f s p e c i e s , obvious d i f f e r e n c e s e x i s t i n g e n e r a l c o l o r p a t t e r n . There are a l s o d i f f e r e n c e s between the two s p e c i e s i n the degree o f s e x u a l d i s p a r i t y t h a t i s probably f u n c t i o n a l i n mate s e l e c t i o n . The c o t t i d s i n g e n e r a l are bottom s k u l k e r s depending upon c r y p t i c c o l o r a t i o n to escape p r e d a t o r y a t t a c k 96 a n d s o m e t i m e s a l s o t o o b t a i n f o o d . B o t h t h e p r e s e n t s p e c i e s a r e c r y p t i c a l l y c o l o r e d . The d i f f e r e n c e s i n p a t t e r n may s u g g e s t d i f f e r e n t h a b i t a t s , b u t t h i s a s s u m p t i o n . i s n o t n e c e s s a r i l y v a l i d a s more t h a n one c r y p t i c p a t t e r n c a n b e e q u a l l y s u c c e s s f u l a g a i n s t t h e same b a c k g r o u n d . The p a t t e r n f i x e d i n t h e g e n o t y p e may h a v e a l a r g e e l e m e n t o f c h a n c e i n i t s a c q u i s i t i o n a n d t h e r e f o r e i s s u b j e c t t o a f a i r d e g r e e o f p h e n o t y p i c p l a s t i c i t y i n i t s u l t i m a t e e x p r e s s i o n . The d i f f e r e n t i a l d e g r e e o f s e x u a l d i m o r p h i s m w i t h i n t h e two s p e c i e s p e r h a p s i s o f more t h a n p a s s i n g i n t e r e s t . A l t h o u g h no i n t e r p r e t a t i o n o f d i f f e r e n c e s o f t h i s s o r t a p p e a r s t o b e a v a i l a b l e i n t h e l i t e r a t u r e o n f i s h i t may be p o s s i b l e t o draw a p a r a l l e l f r o m t h e s i t u a t i o n f o u n d among b i r d s . G r a n t (1964) f o u n d t h a t i n some c l o s e l y r e l a t e d s p e c i e s o f b i r d s t h e d e g r e e o f s e x u a l d i m o r p h i s m i n c o l o r a s w e l l a s b e h a v i o u r v a r i e s w i t h t h e c o m p l e x i t y o f t h e c o m m u n i t y o f w h i c h i t i s a p a r t , t h e more c o m p l e x t h e c o m m u n i t y t h e g r e a t e r t h e d e g r e e o f s e x u a l d i s p a r i t y . I f t h i s p a r a l l e l c a n be v a l i d l y d r a w n i t w o u l d t e n d t o s u g g e s t t h a t M„ j a o k may w e l l i n h a b i t a more c o m p l e x c o m m u n i t y t h a n d o es M, p o l y a c a n t h o c e p h a l u s . T h e r e i s a n o t h e r c a t e g o r y o f e v i d e n c e b e a r i n g u p o n t h e n a t u r e h a b i t a t s o c c u p i e d b y t h e s e two s p e c i e s . T h i s i s i n t h e amount o f m o r p h o m e t r i c a n d m e r i s t i c v a r i a t i o n e x h i b i t e d b y t h e t w o . V a r i a t i o n i s g r e a t e s t i n M, p o l y a c a n t h o c e p h a l u s . I t i s p o s s i b l e t h a t t h i s may b e r e l a t e d t o t h e g r e a t e r v a r i e t y 97 o f h a b i t a t s i t o c c u p i e s . I t seems e q u a l l y p l a u s i b l e to argue t h a t i n t r i n s i c g e n e t i c p l a s t i c i t y made i t p o s s i b l e f o r M. polyacanthocephalus to take advantage o f a wider spectrum o f o p p o r t u n i t i e s f o r e s t a b l i s h i n g i t s e l f than d i d M. j a o k . The i n v a s i o n s o f these d i f f e r e n t h a b i t ats would then open the way f o r f u r t h e r s e l e c t i v e i n f l u e n c e s to p l a y t h e i r p a r t i n m o d i f y i n g the i n d i v i d u a l s . A l t e r n a t i v e l y the s p e c i e s c o u l d be regarded as e x h i b i t i n g a wider t o l e r a n c e t h a t has brought i t i n c o n t a c t w i t h o p p o r t u n i t i e s to s e t up s m a l l d i s c o n t i n u o u s p o p u l a t i o n s w i t h i n which g e n e t i c d r i f t c o u l d l e a d to the a c q u i s i t i o n o f v a r i a n t c h a r a c t e r i s t i c s . The number o f spines or rays i n the f i n s a t f i r s t does not appear to have much ad a p t i v e s i g n i f i c a n c e . However i n the p e c t o r a l and caudal f i n s which are the major elements of p r o p u l s i o n i n these bottom d w e l l i n g forms, the a c q u i s i t i o n or l o s s o f a r a y might have a s i g n i f i c a n t e f f e c t on i t s a b i l i t y to o b t a i n food as w e l l as to escape p r e d a t i o n and thus there would be a d i s t i n c t s e l e c t i v e advantage towards l a r g e r more powerful f i n s . The v a r i a t i o n . i n numbers of spines and rays of the d o r s a l s and a n a l f i n s would not appear to be d i r e c t l y connected w i t h the mechanism o f p r o p u l s i o n or o n l y m i n i m a l l y so. I t i s l i k e l y however t h a t these f i n s are used i n communicative behaviour and mating. The d i f f e r e n t degrees o f v a r i a t i o n i n spine and r a y numbers e x h i b i t e d by these two s p e c i e s c o u l d i n d i c a t e t h a t there i s a d i f f e r e n t i a l i n the s t a b i l i t y o f the gene complexes c o n t r o l l i n g them o r on 98 the o t h e r hand d i f f e r e n t i a l degrees o f phenotypic p l a s t i c i t y . T h i s study a l s o has shown s e v e r a l d i f f e r e n c e s between the two s p e c i e s which have a p p a r e n t l y l i t t l e i f any f u n c t i o n a l s i g n i f i c a n c e . . These a r e : 1. The l o s s o f t h e t h i r d p r e o p e r c u l a r s p i n e by M.. jaok. 2. The morphology o f the l a t e r a l l i n e - O s s i c l e s . 3. The morphology o f the s c a l e s . 4. The presence o f some d i f f e r e n t p r o t e i n s i n the muscle o f the two s p e c i e s . In g e n e r a l c o t t i d s have developed, to a g r e a t e r o r l e s s e r extent, s p i n e s on the preoperculum. B o l i n (1947) suggest t h a t the presence o f f o u r -preopercular s p i n e s i s a p r i m i t i v e f e a t u r e . From numerous o b s e r v a t i o n s i n the f i e l d by the author, the p r e o p e r c u l a r spines o f many c o t t i d s appear to be used as a d e f e n s i v e mechanism. When the animal i s d i s t u r b e d the p r e o p e r c u l a r s are e r e c t e d . In M. polyacantho-cephalus and M. iaok the f i r s t p r e o p e r c u l a r s p i n e s are w e l l developed w h i l e the o t h e r s are much s m a l l e r . The l o s s o f the t h i r d p r e o p e r c u l a r s p i n e by M. jaok would thus not appear to put the i n d i v i d u a l s o f t h i s s p e c i e s a t any disadvantage. T h e r e f o r e i t would seem more probable t h a t the l o s s o f t h i s s p i n e i s the r e s u l t o f g e n e t i c d r i f t r a t h e r than b e i n g brought about by the a c t i o n o f s e l e c t i v e p r e s s u r e . I t appears t h a t the presence o r absence o f the t h i r d p r e o p e r c u l a r 99 spine c o u l d thus be of some s i g n i f i c a n c e as an i n d i c a t o r of p h y l o g e n e t i c r e l a t i o n s h i p w i t h i n the group. S i m i l a r l y the d i f f e r e n c e s i n the morphology o f the l a t e r a l l i n e o s s i c l e s do not appear to have any f u n c t i o n a l s i g n i f i c a n c e . However when d e a l i n g w i t h a system as complex as the nervous system minute s t r u c t u r a l d e v i a t i o n s may i n d i c a t e d i f f e r e n c e s i n f u n c t i o n . Throughout the f a m i l y C o t t i d a e there appears to be a g e n e r a l t r e n d to r e d u c t i o n o f squamation. B o l i n (1947) proposed t h a t the p o s s e s s i o n o f w e l l - d e f i n e d squamation i n the C o t t i d a e was a p r i m i t i v e c h a r a c t e r i s t i c . Squamation i n the genus Myoxocephalus i s q u i t e v a r i a b l e , some s p e c i e s h a v i n g f a i r l y w e l l d i f f e r e n t i a t e d and developed squamation w h i l e o t h e r s l a c k i t e n t i r e l y . Assuming these statements to be v a l i d , i t i s l i k e l y t h a t the p o s s e s s i o n o f s c a l e s i s not o f any f u n c t i o n a l s i g n i f i c a n c e and g e n e t i c d r i f t i s g r a d u a l l y r e d u c i n g t h e i r predominance. In r e c e n t years the use o f e l e c t r o p h o r e t i c a n a l y s i s o f muscle p r o t e i n s as w e l l as hemoglobins, b l o o d plasma p r o t e i n s and enzymes has shown t h a t there i s f r e q u e n t l y p r o t e i n s p e c i f i c i t y between a l l taxonomic l e v e l s down to a t l e a s t the subspecies, (Tsuyuki e t a l . , 1965; Dessauer and Fox, 1956). The p r e l i m i n a r y e x p l o r a t i o n r e p o r t e d here has r e v e a l e d important d i f f e r e n c e s i n the muscle p r o t e i n s o f the two s p e c i e s . The s i g n i f i c a n c e of such d i f f e r e n c e s i s unknown. 100 In the e v o l u t i o n o f animal groups, the number, p o s i t i o n , and shape o f p a r t s i s s u b j e c t to gradual m o d i f i c a t i o n s i n c e no two i n d i v i d u a l s have the same g e n e t i c complement. As wit h m o r p h o l o g i c a l f e a t u r e s , polymorphism and i n t r a s p e c i f i c and geographic v a r i a t i o n are found to occur i n some of the p r o t e i n c o n s t i t u e n t s o f the body between i n d i v i d u a l s o f a s p e c i e s . Presumably the accumulation o f the many d i f f e r e n c e s among p r o t e i n s has come about through the mechanism o f n a t u r a l s e l e c t i o n o f mutations o f p o s i t i v e a d a p t i v e s i g n i f i c a n c e . L i t t l e i s p r e s e n t l y known about the g e n e t i c mechanism o f p r o t e i n i n h e r i t a n c e however the study o f p r o t e i n s o f h y b r i d forms i s b e g i n n i n g to shed some l i g h t on t h i s a r e a . Present evidence suggests t h a t the same h i e r a r c h y o f d i f f e r e n c e s and s i m i l a r i t i e s i n p r o t e i n s e x i s t s f o r c l o s e l y and d i s t a n t l y r e l a t e d taxons. The a p p l i c a t i o n o f p r o t e i n e l e c t r o p h o r e s i s to syst e m a t i c s has been found to depend on the d i s t a n c e between the taxa under i n v e s t i g a t i o n . I t i s g e n e r a l l y acknowledged t h a t when d e a l i n g w i t h i n t r a s p e c i f i c and s p e c i f i c taxonomic l e v e l s e l e c t r o p h o r e s i s u s i n g methods g i v i n g the h i g h e r r e s o l u t i o n are more p r o d u c t i v e . T h i s i s because the p r o b a b i l i t y i s h i g h t h a t p r o t e i n s o f the same m o b i l i t y are i d e n t i c a l i n s t r u c t u r e . The same p r o b a b i l i t y i s not n e c e s s a r i l y a p p l i c a b l e when working w i t h the h i g h e r t a x a . In s t u d i e s w i t h these i n v o l v i n g a method o f lower r e s o l u t i o n such as paper 101 electorphoresis yields more workable re s u l t s since sometimes s i m i l a r i t i e s are masked when higher resolution processes are used. In this stage of our comprehension of the evolution of biochemical units, the s e l e c t i v e value of one protein over another i s not r e a d i l y understood. It i s becoming increasingly obvious as work i n the f i e l d of protein electrophoresis progresses that much information of great systematic value may be gleaned from i t s a p p l i c a t i o n . Since proteins are only a short distance away from the basic unit of inheritance, the gene, i t may be possible i n the future to obtain a somewhat more accurate idea of phylogeny of animal groups than from the more c l a s s i c a l approaches that u t i l i z e characters which are subject to a great amount of phenotypic p l a s t i c i t y i n th e i r ultimate expression. There i s evidence that c e r t a i n aspects of the environment can give r i s e to the introduction of protein fractions or to the disturbance or noraml plasma proteins patterns. This i s p a r t i c u l a r l y evident i n c e r t a i n pathological states i n man and there i s strong evidence that the plasma proteins of deer may be s i m i l a r l y influenced (Van Tets, 1964) . Whether t h i s i s equally applicable to muscle protein and other protein constituents i s not known so care must be taken i n the i n t e r p r e t a t i o n of r e s u l t s . 102 Throughout the course of t h i s study c e r t a i n d i f f e r e n c e s o f a minor nature have been noted: 1. A s l i g h t l y g r e a t e r v a r i a b i l i t y o f the c a u d a l s k e l e t o n o f M. jaok than o f M. polyacanthocephalus. 2. The number and form o f the g i l l r a k e r s p i n u l e s are s l i g h t l y d i f f e r e n t i n the two s p e c i e s . 3 . The number and development o f the o l f a c t o r y l a m e l l a e o f M. jaok i s o f t e n s l i g h t l y h i g h e r than M. polyacanthocephalus. I t i s d i f f i c u l t to imagine t h a t d i f f e r e n c e s o f t h i s magnitude c o n t r i b u t e i n any degree to the f u n c t i o n o f these animals. U n t i l f u n c t i o n a l s i g n i f i c a n c e o f a p o s i t i v e s u r v i v a l v a l u e can be d i s c o v e r e d f o r these d i f f e r e n c e s i t i s tempting to f o l l o w the u s u a l course and to a s s i g n these to the workings o f g e n e t i c d r i f t i n the time s i n c e g e n e t i c i s o l a t i o n o c c u r r e d . There i s however s t i l l one remote p o s s i b i l i t y t h a t c o u l d e x p l a i n these d i f f e r e n c e s . T h i s i s t h a t these d i f f e r e n c e s are a c t u a l l y n e u t r a l to the s u r v i v a l o f the s p e c i e s but are g e n e t i c a l l y l i n k e d w i t h f e a t u r e s of p o s i t i v e s u r v i v a l v a l u e s . The p r e s e n t study has brought to l i g h t areas which sh o u l d be e x p l o r e d i n o r d e r to o b t a i n a coherent p i c t u r e o f the e v o l u t i o n o f t h i s group of f i s h . F i r s t , i n an e v o l u t i o n a r y study i t i s e s s e n t i a l to understand the degree and nature of the i s o l a t i n g mechanisms i n v o l v e d . T h i s w i l l o f n e c e s s i t y i n v o l v e d e t a i l e d s t u d i e s i n t o the 103 comparative ecology and e t h o l o g y of the s p e c i e s , both o f which . are p r e s e n t l y almost w h o l l y unknown. Second, c h a r a c t e r s such as the development o f the p r e o p e r c u l a r spines and the morphology o f the s c a l e s and l a t e r a l l i n e o s s i c l e s , b e i n g a t t r i b u t a b l e to no apparent s e l e c t i v e advantage, have probably a much g r e a t e r v a l u e as p h y l o g e n e t i c i n d i c a t o r s than those o f obvious a d a p t i v e s i g n i f i c a n c e . Future work on the genus should, undertake a c a r e f u l study o f d i f f e r e n c e s o f t h i s n ature. F i n a l l y , " c e r t a i n o f the newer techniques t h a t are b e i n g developed by the p h y s i o l o g i s t s , b i o c h e m i s t s and g e n e t i c i s t s o f f e r g r e a t p o t e n t i a l f o r e x p l o r i n g a t t r i b u t e s of the s p e c i e s not amenable to examination by the more c o n v e n t i o n a l techniques of the s y s t e m a t i s t . Among the p o s s i b i l i t i e s t h a t should be s e r i o u s l y c o n s i d e r e d are expansion o f e l e c t r o p h o r e t i c a n a l y s i s , comparison o f DNA fractions:, immunological t e s t s , and chromosome s t u d i e s . 104 SUMMARY The g e n e r a l body c o l o r a t i o n o f M. polyacanthocephalus i s b a r r e d i n nature w h i l e t h a t o f M„ jaok i s more uniform, M. jaok l a c k s the unpigmented patch a t the base o f the caudal f i n and a l s o the wide dark band possessed by most o f the M. polyacanthocephalus. The membrane between the m a x i l l a r y and the p r e m a x i l l a r y i s pigmented i n M. polyacanthocephalus and unpigmented i n M. jaok. The lower l i p o f M. p o l y a c a n t h o c e p h a l u s , i s h e a v i l y pigmented o r b a r r e d , t h a t o f M, jaok i s u s u a l l y unpigmented and never b a r r e d . Sexual dimorphism i s more h i g h l y developed and more pre-dominant i n M. jaok than i n M. polyacanthocephalus. White spots are found on the base o f the spinous d o r s a l f i n on the p e c t o r a l f i n s and on the trunk o f a d u l t males o f M. iaok b ut are not on those o f M. polyacanthocephalus„ No d i f f e r e n c e . i s apparent between the c e p h a l i c l a t e r a l l i n e systems o f the two s p e c i e s . The o s s i c l e s o f the body l a t e r a l l i n e system are g e n e r a l l y s i m i l a r i n s t r u c t u r e however those o f M. jaok are more elongate and narrower and the pore c a n a l openings are d i f f e r e n t i n s t r u c t u r e than those o f M. polyacanthocephalus„ The s c a l e s are f i r s t formed when a s i z e o f about 15 cm. 105 t o t a l l e n g t h i s a t t a i n e d . The s c a l e s o f M. polyacanthocephalus are a l l of one b a s i c type. The s c a l e s o f M. Iaok are o f two b a s i c t ypes: the s t e l l a t e t u b e r c l e above the l a t e r a l l i n e and the s m a l l e r s p i n a t e s c a l e s s i m i l a r to those o f M. polyacanthocephalus below the l a t e r a l l i n e . The p e c t o r a l p a p i l l a e o f the a d u l t males o f both s p e c i e s appear to be i d e n t i c a l . The p e c t o r a l p a p i l l a e of M. polyacanthocephalus do not extend p r o x i m a l l y as f a r as those o f M. jaok. P e l v i c p a p i l l a e are s i m i l a r i n o r i g i n and s t r u c t u r e b u t do not occur as f r e q u e n t l y o r as f a r p r o x i m a l l y on M. polyacanthocephalus as on M. i a o k . A l l the spines o f the o p e r c u l a r apparatus are the same i n both s p e c i e s w i t h the e x c e p t i o n o f the t h i r d p r e o p e r c u l a r s p i n e . The t h i r d p r e o p e r c u l a r spine i s w h o l l y l a c k i n g i n M. i aok but i s p r e s e n t e i t h e r i n a rudimentary form o r f u l l y developed i n M. polyacanthocephalus. The muscles o f the cheek r e g i o n appear to be i d e n t i c a l i n both s p e c i e s . The muscles o f the o p e r c u l a r apparatus are the same i n number, s t r u c t u r e , and f u n c t i o n i n both s p e c i e s b u t appear to be s l i g h t l y l e s s w e l l developed on the average i n M. i a o k . 106 The muscles o f the v e n t r a l s u r f a c e o f the head are i d e n t i c a l i n both s p e c i e s . The caudal s k e l e t o n s o f both s p e c i e s are s i m i l a r . That o f M. iaok e x h i b i t s somewhat more v a r i a t i o n i n r e g a r d to the number o f branched and unbranched ray s , and the number o f n e u r a l and haemal spines which are m o d i f i e d . The c a u d a l musculature o f both s p e c i e s i s i d e n t i c a l . The number and s t r u c t u r e o f the g i l l arches are i d e n t i c a l i n both s p e c i e s . The g i l l r a k e r s are s i m i l a r i n s i z e , number, and p o s i t i o n i n both s p e c i e s . The s p i n u l e s on the g i l l r a k e r s o f M. iaok are longer and s t r o n g e r and somewhat l e s s numerous than those o f M. polyacanthocephalus. The g e n e r a l s t r u c t u r e o f the o l f a c t o r y r o s e t t e s are s i m i l a r i n b oth s p e c i e s . The number o f o l f a c t o r y l a m e l l a e tends to be somewhat h i g h e r i n M. jaok. There are some important d i f f e r e n c e s i n the muscle myogens of the two s p e c i e s . The range of the number o f d o r s a l f i n s p i n e s i s the same f o r both s p e c i e s however the predominant number i s 10 i n M. polyacanthocephalus and 9 i n M. jaok. The number of second d o r s a l f i n rays ranges from 10-15, 14 b e i n g the most predominant i n M. polyacanthocephalus. 107 The number o f s e c o n d d o r s a l f i n r a y s r a n g e s f r o m 14-16, 15 b e i n g t h e most p r e d o m i a n t i n M. j a o k . The number o f b r a n c h e d c a u d a l r a y s i s t h e same f o r b o t h s p e c i e s . The number o f a n a l f i n r a y s r a n g e f r o m 8-15, 12 b e i n g t h e most p r e d o m i n a n t i n M. p o l y a c a n t h o c e p h a l u s . I n M. i a o k t h e number o f a n a l f i n r a y s r a n g e s f r o m 12-15, w i t h b o t h 13 a n d 14 b e i n g e q u a l l y p r e d o m i n a n t . More v a r i a t i o n i s e x h i b i t e d i n v e r t e b r a l number b y M. p o l y a c a n t h o c e p h a l u s t h a n b y M. j a o k however t h e most p r e d o m i a n t number i s 35 f o r b o t h s p e c i e s . The number o f l a t e r a l l i n e o s s i c l e s i s e s s e n t i a l l y t h e same i n b o t h s p e c i e s . The number o f t h e l o n g e s t p e c t o r a l r a y r a n g e s f r o m 4-8, 6 b e i n g t h e most common f o r M. p o l y a c a n t h o c e p h a l u s . The number o f t h e l o n g e s t p e c t o r a l r a y r a n g e s f r o m 2-5, w i t h 3 t h e most common i n M. i a o k . The number o f t h e l o n g e s t c a u d a l r a y i n M. p o l y a c a n t h o c e p h a l u s r a n g e s f r o m 3-9 w i t h 8 t h e most p r e d o m i n a n t . I n M. i a o k t h e number o f t h e l o n g e s t c a u d a l r a y r a n g e s f r o m 2-3 w i t h b o t h b e i n g e q u a l l y p r e d o m i n a n t . The number o f t h e l o n g e s t p e l v i c r a y i s s i m i l a r f o r b o t h s p e c i e s . The number o f t h e l o n g e s t f i r s t d o r s a l s p i n e i s s i m i l a r i n b o t h s p e c i e s , t h e most p r e d o m i n a n t number b e i n g 4. 108 The number of the longest second dorsal ray i s si m i l a r i n both species, the most common number i s 4. The number of the longest anal f i n ray i s si m i l a r for both species however the most predominant number i s 6 for M.  polyacanthocephalus and 7 for M. j a o k . The morphometric and age rela t e d measurements are si m i l a r for both species. Only the depth of caudal peduncle against length of the anal f i n base and the depth of caudal peduncle against the length of second dorsal f i n base, were found to y i e l d useful differences between the two species. In general M. polyacanthocephalus i s a more robust species than i s M. Iaok. In general the rate of growth of most body parts i n r e l a t i o n to length i s somehwat greater i n M. polyacanthocephalus than i n M. jaok. M. jaok has a more li m i t e d depth d i s t r i b u t i o n than M. polyacanthocephalus. The adults of both species probably inhabit deeper water than do the younger i n d i v i d u a l s . Both species appear to inhabit the same waters and eat the same foods when occurring sympatrically. 109 LITERATURE CITED B o l i n , R. R. 194.7. 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S t a r c h Gels and i t s A p p l i c a t i o n t o Studie s o f Serum P r o t e i n s . Adv. P r o t . Chem. 14:65. Tinbergen, N. 1951. The Study o f I n s t i n c t . Oxford: Clarendon P r e s s . T i s e l i u s , A. 1937. A New Apparatus f o r E l e c t r o p h o r e t i c A n a l y s i s o f C o l l o i d a l M i x t u r e s . T r a n s . Faraday Soc. 33:524-531. Tsuyuki, H., E. Roberts, and W. E. Vanstone. 1965a. Comparative Zone Electropherogram o f Muscle Myogens and Bloo d Hemoglobins o f Marine and Freshwater V e r t e b r a t e s and T h e i r A p p l i c a t i o n t o Bi o c h e m i c a l S y s t e m a t i c s . J . Fish„ Res. Bd. Canada, 22 (1) :203-213. Tsuyuki, H., E. Roberts, W. E. Vanstone, and J . R. Markert. 1965b. The Species S p e c i f i c i t y and Constancy o f Muscle Myogen and Hemoglobin Electropherograms o f Oncoryhnchus. J . F i s h . Res. Bd. Canada, 22(1):215-217. Van T e t s , P. A. 1964. A S t a r c h - G e l E l e c t r o p h o r e t i c Study o f Some o f the Sources o f V a r i a t i o n i n the Blood Sera o f Deer o f the Genus O d o c o i l e u s . M.Sc. T h e s i s , Dept. o f Zoology, U n i v e r s i t y o f B r i t i s h Columbia. 

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