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Lower Cambrian archaeocyatha from the Yukon Territory Kawase, Yoshio 1956-12-31

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LOWER CAMBRIAN ARCHAEOCYATHA PROM THE YUKON TERRITORY by YOSHIO KAWASE B.A.Sc, U n i v e r s i t y of B r i t i s h Columbia, 195* A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n the Department of GEOLOGY AND GEOGRAPHY We accept t h i s t h e s i s as conforming t o the standard required from candidates f o r the degree of MASTER OF APPLIED SCIENCE Members of the Department of GEOLOGY AND GEOGRAPHY THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1956 i ABSTRACT Archaeocyatha from the Lower Cambrian of Wolf Lake and Quiet Lake areas i n the Yukon T e r r i t o r y are described and i l l u s t r a t e d . The f o s s i l s occur i n carbonate rocks and are w e l l preserved. Much of the necessary s t r u c t u r a l de t a i l of the f o s s i l s i s c l e a r l y observed i n t h i n - s e c t i o n s and on p o l i s h e d surfaces of the specimens. The c o l l e c t i o n contains twenty-three s p e c i e s , twelve of which are new speciesf. The new species described are: A j a c i c y a t h u s yukonensis, Coscinocyathus m u l t i p o r u s . Coseinocyathus c as s i a r i ens i s, Coscinocyathus i n e q u i v a l l u g , Coscinocyathus s e r r a t u s , Coscinocyathus v e r o n i c u s , Coscinocyathus t u b i c o r n u s , Carinacyathus p e r f o r a t u s , Pyenoidocyathus s o l i d u s , L o c u l i c y a t h u s e l l i p t i e u s , Metacoscinus p o o l e n s i s , and Claruscyathus k e t z a e n s i s . The genera Carinacyathus and Loculicyathus are reported f o r the f i r s t time i n North America. The Yukon fauna i s dominated by Coscinocyathidae and Pycnoidocyathidae, showing c l o s e r e l a t i o n s h i p t o faunae i n the C o r d i l l e r a n region of B r i t i s h Columbia. I t a l s o shows r e l a t i o n s h i p to S i b e r i a n and A u s t r a l i a n faunae. This fauna i s very d i f f e r e n t from the archaeocyathid assemblages i n Nevada and C a l i f o r n i a , where the dominant forms are Ethmophyllidae and A j a c i c y a t h i c l a e . Arehaeocyatha have been instru m e n t a l i n de t e r  mining the age of rocks u n d e r l y i n g a l a r g e area of the Yukon T e r r i t o r y . ACKNOWLEDGMENTS I wish t o express my s i n c e r e thanks t o Dr. V.J. O k u l i t c h , P r o f e s s o r and Chairman, D i v i s i o n of Geology, f o r h i s many suggestions and c o n s t r u c t i v e c r i t i c i s m s . I am indebted to him f o r h i s i n s t r u c t i o n s and help i n the prep a r a t i o n of i l l u s t r a t i o n s , and a l s o f o r h i s t r a n s l a t i o n of Russian p u b l i c a t i o n s . I wish to thank Dr. Aho, Dr. T r e t t i n , and the Geo l o g i c a l Survey of Canada f o r p r o v i d i n g the m a t e r i a l f o r t h i s t h e s i s . Mr. J.A. Donnan, g e o l o g i c a l t e c h n i c i a n , i n s t r u c t e d me i n the p r e p a r a t i o n of t h i n s e c t i o n s . Mr. J . McGraw a s s i s t e d i n the photography of pol i s h e d sections. F i n a l l y , I am g r a t e f u l t o my f e l l o w - s t u d e n t s , Mr. D.N. H i l l h o u s e and Mr. R.G. Greggs, f o r t h e i r help and d i s c u s s i o n i n the pr e p a r a t i o n of t h i s t h e s i s . LOWER CAMBRIAN ARCHAEOCYATHA FROM THE YUKON TERRITORY INTRODUCTION This t h e s i s i s based on a study of Lower Cambrian Archaeocyatha c o l l e c t e d by A. Aho and W. Padgham of the B r i t i s h Yukon E x p l o r a t i o n Company, and by W.H. Poole of the Geo l o g i c a l Survey of Canada i n the Yukon T e r r i t o r y . Through the courtesy of Aho and of the G e o l o g i c a l Survey of Canada, these c o l l e c t i o n s were made a v a i l a b l e f o r study. Another c o l l e c t i o n from the same area, k i n d l y presented by H. T r e t t i n , was examined but not studi e d i n d e t a i l . About twenty-four specimens were i n Aho's and Padgham's c o l l e c t i o n and over f i f t y i n the c o l l e c t i o n made by Poole. The f o s s i l s , which oecur In dark, f i n e - g r a i n e d carbonate r o c k s , were, f o r the most p a r t , w e l l preserved and r e l a t i v e l y l a r g e . T h e i r study was thus made e a s i e r . The present work c o n s i s t s mainly of d e t a i l e d de s c r i p t i o n s and i d e n t i f i c a t i o n s of the specimens. The ever V p e r p l e x i n g problems on the causes of the e x p l o s i v e , world wide d i s t r i b u t i o n and the sudden disappearance of Archaeocyatha i n Cambrian time, and the s t u d i e s of ecology, ontogeny, or physiology are not discussed here. These problems have been de a l t w i t h elsewhere by Hinde, T a y l o r , V o l o g d i n , the Bedfords, Simon, O k u l i t c h , and other l e a d i n g p a l a e o n t o l o g i s t s . No attempt i s made i n t h i s t h e s i s to d i s c u s s the pros and cons of t h e i r t h e o r i e s and hypotheses. The g e n e r a l , b a s i c c h a r a c t e r i s t i c s of Archaeocyatha are given i n the f i r s t chapter of t h i s t h e s i s . In the second chapter the methods and c r i t e r i a used i n c l a s s i f y i n g the archaeocyathids are discussed. A l s o , the f o s s i l l o c a l i t i e s and the geology of the area are described b r i e f l y . The greater part of the t h e s i s , as stated e a r l i e r , concerns the systematic d e s c r i p t i o n of the archaeocyathids from the Yukon. In Chapter I I I , twenty-three s p e c i e s , of which twelve are new, are described. From the i n v e s t i g a t i o n of these f o s s i l s , conclusions are drawn i n the f i n a l chapter. O r i g i n a l l y , i t was hoped, by the study of these f o s s i l s , to e s t a b l i s h f a u n a l zones of the Lower Cambrian. This was found to be impossible because no data on the d e t a i l e d s t r a t i g r a p h y were a v a i l a b l e and because the f o s s i l s were not c o l l e c t e d i n a systematic manner. With d e t a i l e d s t r a t i g r a p h i c work i n conjunction w i t h systematic c o l l e c t i o n s of f o s s i l s , i t may be p o s s i b l e to set up archaeocyathid f a u n a l zones. This zoning, i f i t can be e s t a b l i s h e d , w i l l be i n v a l u a b l e i n r e s o l v i n g some of the above mentioned problems, such as phylogeny, of Arehaeocyatha. This s m a l l c o n t r i b u t i o n t o the p a l a e o n t o l o g i c a l s t u d i e s of Arehaeocyatha, i t i s hoped, w i l l be of value i n f u r t h e r s t u d i e s . CONTENTS Page ABSTRACT i ACKNOWLEDGMENTS . . . i i i INTRODUCTION ' i v Chapter I GENERAL CHARACTERISTICS OF THE ARCHAEOCYATHA I n t r o d u c t i o n 1 Morphology 3 A f f i n i t i e s 6 C l a s s i f i c a t i o n . . . 8 Chapter I I METHODS OF STUDY AND FOSSIL LOCALITIES I n t r o d u c t i o n 10 The Aho and Padgham C o l l e c t i o n 11 The G e o l o g i c a l Survey of Canada C o l l e c t i o n . . 13 P r e p a r a t i o n and Study of F o s s i l s 15 Chapter I I I SYSTEMATIC DESCRIPTIONS OF ARCHAEOCYATHA FROM THE YUKON TERRITORY Faunal L i s t 17 D e s c r i p t i o n of Species 18 A j a c i c y a t h i d a e . 18 Ajaeicyathus p u r c e l l e n s i s 19 A.jacicyathus yukonensis 20 Ethmophyllidae 23 Ethmocoscinus sp 23 Coscinocyathidae 25 Coscinocyathus dentocanis . . 25 Coscinocyathus multiporus 26 Coscinocyathus c a s s i a r i e n s i s 29 Coscinocyathus i n e q u i v a l l u s 31 Coscinocyathus s e r r a t u s 34 Coscinocyathus veronicus 36 Coscinocyathus tubicornus 38 Coscinocyathus sp 39 Carinacyathus p e r f o r a t u s . . . . 41 Page Arehaeocyathidae 45 Archaeocyathus c f . a t l a n t i c u s 45 Archaeocyathus (?) sp" ". T~ 47 Pycnoidocyathidae 48 Pycnoidocyathus amourensis 48 Pycnoidocyathus columbianus 50 Pycnoidocyathus c f . o c c i d e n t a l i s 51 Pycnoidocyathus c f . d i s s e p i m e n t a l i s . . . . 54 Pycnoidocyathus s o l i d u s 55 Loculicyathus e l l i p t i c u s 58 Metacoscinidae 60 Metacoscinus poolensis 60 Metacoscinus sp 62 Claruscyathus Ketzaensis 64 Chapter IV SUMMARY AND CONCLUSION A f f i n i t i e s to Other Faunae 67 Age of the Rocks 68 Suggestions f o r Further Studies . 69 BIBLIOGRAPHY 71 EXPLANATION OF PLATES 75 ILLUSTRATIONS Figure Page, 1, O u t l i n e Map Showing World Wide D i s t r i b u t i o n of Archaeocyatha . . . . 2. Diagrammatic Sketch of a T y p i c a l Archaeocyathid Showing the Major S k e l e t a l Elements Table 1. Table of Formations P l a t e I . A j acicyathus p u r c e l l e n s i s , A.-|acicyathus  yukonensis, Ethmocoscinus sp., Coscinocyathus dentocanis, Coscinocyathus  m u l t i p o r u s , Coscinocyathus c a s s i a r i e n s i s Facing Page . . . . 75 I I . Coscinocyathus i n e q u i v a l l u s , Coscinocyathus  s e r r a t u s , Coscinocyathus v e r o n l c u s , Coscinocyathus t u b i c o r n u s , ~" Coscinocyathus sp. Facing Page . . . . 77 I I I . Carinacyathus p e r f o r a t u s , Archaeocyathus  c f . a t l a n t i c u s , Archaeocyathus (?) sp." Facing Page . . . . 79 IV. Pycnoidocyathus amourensis, Pycnoidocyathus  columbianus, Pycnoidocyathus c f . o c c i d e n t a l i s % Pycnoidocyathus c f . d i s s e p i m e n t a l i s , Pycnoidocyathus' s o l i d u s Facing Page . . . . 80 V. Loculicyathus e l l i p t i c u s , Metacoscinus  p o o l e n s i s , Metacoscinus sp., Claruscyathus k e t z a e n s i s Facing Page . . . . 81 2 4 14 CHAPTER I GENERAL CHARACTERISTICS OF THE ARCHAEOCYATHA I n t r o d u c t i o n Archaeocyathids, now c l a s s i f i e d as an independent phylum Arehaeocyatha, i n the Sub-Kingdom Parazoa, were e x c l u s i v e l y Cambrian marine organisms w i t h world wide d i s t r i b u t i o n (Figure 1 ) . They i n h a b i t e d every Cambrian sea i n l a r g e numbers and i n extremely d i v e r s e forms i n d i  c a t i v e of an exp l o s i v e e v o l u t i o n . They l i v e d a s e s s i l e , benthonic l i f e on calcareous bottoms, forming i n some l o c a l i t i e s almost r e e f - l i k e s t r u c t u r e s . 2 F i g u r e 1, O u t l i n e Map Showing World Wide  D i s t r i b u t i o n of Arehaeocyatha I t seems i n d i s p u t a b l e that archaeocyathids l i v e d i n great numbers i n shallow, r e l a t i v e l y c l e a r water zones p a r a l l e l t o the c o a s t l i n e s of the Cambrian seas. However, the e x t r a o r d i n a r y and robust development of t h i s phylum was s h o r t - l i v e d . Archaeocyathids apparently could not t o l e r a t e muddy-water con d i t i o n s nor defend them selv e s against the encroachment of the algae. In North America and A u s t r a l i a , archaeocyathids became e x t i n c t , 3 l e a v i n g no recognizable descendants at the c l o s e of the Lower Cambrian. In E u r a s i a , Archaeocyatha may have con tinued to the end of Middle Cambrian, but recent Russian reports by Zhuravleva seem to i n d i c a t e t h e i r e x t i n c t i o n at the c l o s e of the Lower Cambrian. Archaeocyatha made a sudden, c a t a s t r o p h i c disappearance. Morphology The d e l i c a t e and f r a g i l e skeletons of Archaeocyatha are composed of calcium carbonate but some, l i k e the A u s t r a l i a n specimens, are s i l i c i f i e d . S i z e and shape of skeletons are extremely v a r i a b l e . The shape of the skeletons v a r i e s from r e g u l a r c o n i c a l and c y l i n d r i c a l cups to f l a t , expanding saucer-shaped forms. In c r o s s - s e c t i o n , cups are q u i t e o f t e n e l l i p t i c a l w h i l e others are c r e n u l a t e d . Although great d i v e r s i t y i n form e x i s t s , the most t y p i c a l skeletons are goblet- or vase-shaped. In s i z e , skeletons may range from a few m i l l i  meters to over 50 centimeters i n diameter i n the f l a t expanding types, but the m a j o r i t y are l e s s than 30 m i l l i  meters i n diameter. U s u a l l y , only short fragments are c o l l e c t e d but Archaeocyatha may grow con s i d e r a b l y i n l e n g t h . Specimens of two or three f e e t i n l e n g t h w i t h diameters of four inches have been reported by B i l l i n g s . The more common, simpler type of Arehaeocyatha skeletons c o n s i s t s of an outer cup or cone and an inner cup so that the sk e l e t o n i s double w a l l e d (Figure 2 ) . The inner w a l l i s g e n e r a l l y c o n c e n t r i c w i t h the outer w a l l , but i t may be incomplete towards the apex or s p i t z area of the cone. The space between the w a l l s , c a l l e d the Central cavil y Outer j Inner wall Figure 2. Diagrammatic Sketch of a T y p i c a l  Archaeocyathid Showing the " Major S k e l e t a l Elements 5 i n t e r v a l l u m , i s occupied by s e v e r a l d i f f e r e n t s t r u c t u r a l elements which support the inner w a l l some d i s t a n c e away from the outer w a l l and a l s o subdivide the space i n t o compartments. These supports may be i n the form of s t r a i g h t , v e r t i c a l , r a d i a l p l a t e s c a l l e d p a r i e t i e s ; curved, i r r e g u l a r and anastomosing p a r i e t i e s or l^ a e n i a e ; and h o r i z o n t a l or arched t a b u l a r p l a t e s c a l l e d tabulae. These elements may be f u r t h e r complicated and strengthened by dissepiments, s y n a p t i c u l a e , c e l l u l a r or tubula r s t r u c t u r e s , and v e s i c u l a r t i s s u e s . In n e a r l y a l l cases, these s t r u c t u r a l elements and w a l l s are perforated by numerous pores and c a n a l - l i k e channels. The inner w a l l encloses the c e n t r a l c a v i t y which i s present i n most genera. The c e n t r a l c a v i t y , completely open upwards, was i n a l l p r o b a b i l i t y f r e e of l i v i n g t i s s u e though l i n e d by i t . In some genera, however, the lower parts of the c a v i t y i s occupied by i r r e g u l a r v e s i c u l a r t i s s u e s . Minor s t r u c t u r e s may o c c a s i o n a l l y p r o j e c t a short distance from the inner w a l l i n t o the c e n t r a l c a v i t y r e g i o n . On some specimens of Arehaeocyatha are preserved exothecal l a m e l l a e , whieh are i r r e g u l a r masses of t i s s u e , f i l a m e n t s , or f i b e r s attached to the outer s i d e of the s k e l e t a l cup. The exact nature and f u n c t i o n of these extran eous, c a n c e r - l i k e growths are not f u l l y understood, but they may have, i n p a r t , served as h o l d - f a s t or anchoring 6 devices and as p r o t e c t i o n f o r the cup. A f f i n i t i e s Archaeoeyathid a f f i n i t i e s have been a c o n t r o v e r s i a l subject ever s i n c e B i l l i n g s described and named the f i r s t Archaeocyatha. They have been classed w i t h sponges, c o r a l s , protozoans, and calcareous algae. I n 1889, HInde, review ing a l l archaeocyathids known at that time, disproved t h e i r a f f i n i t i e s w i t h the protozoans ( F o r a m i n i f e r a ) . L a t e r , Taylor ( 1 9 1 0 ) made h i s memorable c o n t r i b u t i o n to the knowledge of Archaeocyatha by p o i n t i n g out the absence of r e l a t i o n s h i p between them and algae. In subsequent ye a r s , Archaeocyatha were c l a s s i f i e d w i t h e i t h e r c o r a l s or sponges u n t i l O k u l i t c h ( 1 9 3 5 ) showed that Archaeocyatha do not belong w i t h c o r a l s but are a separate c l a s s of the phylum P o r i f e r a . R ecently, a c r i t i c a l reviewwas made by O k u l i t c h and De Laubenfels ( 1 9 5 3 ) as to the v a l i d i t y of t h i s separate c l a s s . Because they found that i t was impossible t o place the Archaeocyatha e i t h e r w i t h the phylum P o r i f e r a or w i t h any other de f i n e d major group of organisms, they erected a new phylum c a l l e d Archaeocyatha. Because archaeocyathids are s t i l l mistaken at times f o r sponges or s o l i t a r y c o r a l s , t h e i r main s i m i l a r i t i e s and 7 d i f f e r e n c e s w i l l be b r i e f l y discussed here. At a casual glance, archaeocyathids g r e a t l y resemble c o r a l s and sponges, e s p e c i a l l y i n s u p e r f i c i a l f e a t u r e s . The general c o n i c a l form and symmetrically arranged r a d i a l p a r i e t i e s of Areh aeocyatha are s t r i k i n g l y s i m i l a r i n appearance to the s t r u c t u r e of s o l i t a r y c o r a l s , w h i l e the form, c e n t r a l c a v i t y , canal system, and p e r f o r a t e d s k e l e t o n are reminiscent of some present-day sponges. However, d i s s i m i l a r i t i e s of Arehaeocyatha from sponges and c o r a l s g r e a t l y outweigh these s u p e r f i c i a l resemblances. G k u l i t c h (1955a) has l i s t e d the e s s e n t i a l d i f f e r e n c e s as f o l l o w s : D i s s i m i l a r i t i e s from Corals (1) presence of porous inner w a l l ; (2) s o f t parts probably confined to i n t e r v a l l u m and p o s s i b l y a l i n i n g on outer and inner w a l l s , very u n l i k e anthozoan polyps; (3) l a c k of r e g u l a r i t y i n plan of the p a r i e t i e s , which may be increased or reduced i n haphazard manner; (4) s t r u c t u r e of p a r i e t i e s , i n d i c a t i n g l a c k of homology w i t h septa of c o r a l s ; (5) absence of p a r i e t i e s i n a l l n e p i o n i c skeletons ( s p i t z e s ) and i n some a d u l t i n d i v i d u a l s ; (6) n e a r l y constant width of the i n t e r v a l l u m ; (7) perforated nature of tabulae i n c o n t r a s t to imperforated tabulae of c o r a l s ; (8) wide d i s s i m i l a r i t y In form of many archeao- cyathids from c o r a l s ; and (9) geologic a n t i q u i t y of archaeocyathids and s e p a r a t i o n from o l d e s t known c o r a l s by a great time span. D i s s i m i l a r i t i e s from Sponges (1) sponges i n v a r i a b l y l a c k p a r i e t i e s and none have laminar outer and inner w a l l s such as are possessed by archaeocyathids; 8 although a few f o s s i l sponges seem to have s t i f f e n e d c l o a c a l w a l l s , these probably represent post-mortem a l t e r a t i o n ; although some sponges possess a c o r t e x , t h i s c o n s i s t s of s p i c u l e s which do not form a w a l l ; the g r a n u l a r - l a m e l l a r s k e l e t o n of archaeo cyathids d i f f e r s g r e a t l y from the s p i c u l a r s k e l e t o n of sponges both i n mode of d e v e l  opment and general s t r u c t u r e ; the Archaeocyatha are confined t o Cambrian rocks, whereas the o l d e s t known calcareous sponges occur i n the Devonian; and i n archaeocyathids an i n i t i a l l y imperforate s p i t z gives r i s e to perforated w a l l s i n which i n c r e a s i n g s i z e of pores may leave only slender rods between them, but the sponge s k e l e t o n i s b u i l t up from somewhat wide l y separated n e e d l e - l i k e s p i c u l e s i n e a r l y ontogeny to a more or l e s s compact s t r u c t u r e of crowded s p i c u l e s i n mature growth. With c a r e f u l o b s e r v a t i o n , these d i f f e r e n c e s between archaeocyathids and sponges or c o r a l s can e a s i l y be detected. C l a s s i f i c a t i o n C l a s s i f i c a t i o n s of archaeocyathids have been pro posed by Walcott (1886), T a y l o r ( 1 9 1 0 ) , O k u l i t c h ( 1 9 3 5 , 1943), Vologdin (1937, 1940), Bedford and Bedford (1939), and Simon ( 1 9 3 9 ) . The e a r l i e r proposed c l a s s i f i c a t i o n s are now disregarded. The c l a s s i f i c a t i o n adopted by O k u l i t c h , V o l o g d i n , and the Bedfords are b a s i c a l l y s i m i l a r . The l a t e s t c l a s s i f i c a t i o n of archaeocyathids has been proposed by (2) (3) (4) (5) (6) 9 O k u l i t c h (1955a)> which i s a modified v e r s i o n of h i s e a r l i e r (194-3) work. In t h i s t h e s i s , the c l a s s i f i c a t i o n proposed by O k u l i t c h ( 1955a) was s t r i c t l y adhered to i n order t o avoid confusing the already overloaded nomenclature w i t h i n v a l i d genus names. He has d i v i d e d Phylum Arehaeocyatha i n t o three classes - Monocyathea, Archaeocyathea, and Antho- cyathea - and has made systematic d e s c r i p t i o n s of a l l known genera of the c l a s s e s . He has a l s o given a f t e r each genus, i t s homonyms, synonyms, and type species w i t h i t s author and date of f i r s t p u b l i c a t i o n . CHAPTER I I METHODS OF STUDY AND FOSSIL LOCALITIES I n t r o d u c t i o n F o s s i l s of the two c o l l e c t i o n s s t u d i e d f o r t h i s t h e s i s came from a number of l o c a l i t i e s i n the Yukon T e r r i  t o r y . One c o l l e c t i o n was made by A. Aho and W. Padgham, and the other by W.H.Poole. Arehaeocyatha occur mainly i n dark carbonate rocks which are f i n e - g r a i n e d , massive to o o l i t i c i n t e x t u r e . Some specimens are p a r t i a l l y and a few completely weathered out from the lime m a t r i x . On the whole, the f o s s i l s are w e l l preserved, w i t h a few replaced by, c a l c i t e and a few fragmental because of the s l a t y nature of some limestone. Because the r e c o g n i t i o n of the d i f f e r e n t genera and species depends on the d e t a i l s of the s k e l e t o n , t h i n - s e c t i o n s and p o l i s h e d s e c t i o n s were made. Transverse and l o n g i t u d i n a l s e c t i o n s were cut of each specimen, and oblique s e c t i o n s were cut i n some. The a c i d etching technique, which can be a p p l i e d to s i l i c i f i e d specimens, could not be used f o r these specimens because of t h e i r calcareous nature. The Aho and Padgham C o l l e c t i o n In the summer of 1 9 5 5 , Aho and Padgham discovered Lower Cambrian f o s s i l s w h i l e doing d e t a i l e d mapping of the Kay Group mining claims f o r the B r i t i s h Yukon E x p l o r a t i o n Company. The claims s t r a d d l e the ridge which separates the head waters of White Creek and Ketza R i v e r i n the P e l l y Mountains i n the Quiet Lake Area (Department of Mines and Tech n i c a l Surveys, N a t i o n a l Topographic S e r i e s , Map Sheet 1 0 5 F ) , Whitehorse Mining D i s t r i c t , Yukon T e r r i t o r y . This area i s e a s i l y a c c e s s i b l e from two lakes on which planes can land: (a) Bruce Lake, from which t h i r t y miles of good t r a i l leads up Ketza R i v e r , and (b) G r a y l i n g Lake, from which i t i s a f i f t e e n m i l e hike up White Creek. The area can a l s o be reached i n two days by horse from the Canol Road, which runs i n a north-south d i r e c t i o n about t h i r t y miles t o the east. The exact f o s s i l l o c a l i t y ( l a t i t u d e 6 l ° 3 1 ' ; l o n g i  tude 1 3 2 ° 1 5 ' ) i s approximately 1000 f e e t northwest from the northwest corner of the Kay No. 31 c l a i m and on the t r a i l l e a d i n g to the Conwest camp which i s eight miles n o r t h e r l y from t h i s area. The l o c a l i t y i s marked on a map accompanying Aho's (1955) r e p o r t , "Geologic Report on the Kay Group of Claims and Upper White Creek, Ketza River Area, Yukon T e r r i  t o r y " , which was submitted t o the Department of Mines as assessment work. 12 Rocks of the Kay Group of claims and adjacent upper White Creek area, as reported by Aho, c o n s i s t c h i e f l y of marine sediments which have been f o l d e d , f a u l t e d , and weakly metamorphosed. P h y l l i t e , limestone, dolomite, and q u a r t z i t e are the main rock types. The Lower Cambrian rocks of limestone and p h y l l i t e are exposed along a N 7 0 ° W a n t i c l i n a l f o l d . The f o l l o w i n g s t r a t i g r a p h i c sequence of the area, i n descending order, i s reported by Aho: Apparent S t r a t i g r a p h i c S e c t i o n at Upper White Creek White, brown, and gray massive p y r i t i c q u a r t z i t e , minor greenish gray c h e r t , limestone and p h y l l i t e w i t h a n k e r i t e (?) impure q u a r t z i t e and gradations to l i m y s c h i s t s and minor green p h y l l i t e forming the bottom of t h i s s e c t i o n . Black p h y l l i t e or s l a t e (may c o n t a i n l o c a l s l a t y limestones) Massive to t h i n bedded'*, buff weathering dolomite w i t h l o c a l chert nodules and t h i n ribbon chert beds. Thin bedded s l a t y limestone and o o l i t i c limestone. L o c a l l y absent. Brown p h y l l i t e ( l o c a l l y limy) grading downward to gray and black p h y l l i t e . Blue-gray, massive f o s s i l i f e r o u s Lower Cambrian limestone ( l o c a l l y o v e r l a i n by 50 f e e t of brown p h y l l i t e ) . S e v e r a l beds of s l a t y or s h a l y limestone a l t e r n a t i n g w i t h g r a y i s h brown p h y l l i t e and grading downward i n t o gray p h y l l i t e at l e a s t s e v e r a l hundred feet t h i c k w i t h minor l i m y and sandy beds. Thickness S e v e r a l hundred feet 100 f e e t 100 t o 200 f e e t 50 f e e t ? 500 f e e t 150 to 200 f e e t 500 feet 13 Aho s t a t e s that the s e c t i o n holds f o r t h i s l o c a l  i t y , but does not preclude some degree of t h i c k e n i n g by t h r u s t i n g or i s o c l i n a l drag f o l d i n g , e s p e c i a l l y i n the i n  competent p h y l l i t e members. More r e g i o n a l geology of the area i s not known at the present time. The G e o l o g i c a l Survey of Canada C o l l e c t i o n During the f i e l d seasons of 1951 to 1954 i n c l u s i v e , W.H.Poole of the G e o l o g i c a l Survey of Canada mapped the Wolf Lake Area, Yukon T e r r i t o r y (Department of Mines and T e c h n i c a l Surveys, Sheet 105B; G e o l o g i c a l Survey of Canada P r e l i m i n a r y Map 55-21). With the c o n s t r u c t i o n of the A l a s k a Highway, t h i s area i s now r e a d i l y a c c e s s i b l e . Areas remote from the highway can be reached by s u i t a b l y equipped a i r c r a f t , which can land on any one of the numerous l a k e s . Pack horses can be used to great advantage anywhere i n the area. In the course of h i s f i e l d work, Poole c o l l e c t e d a number of Lower Cambrian f o s s i l s from d i f f e r e n t l o c a l i t i e s , which are marked on the P r e l i m i n a r y Map 55-21 of the Wolf Lake Area. F o s s i l s s t u d i e d f o r t h i s t h e s i s came from the f o l l o w i n g p l a c e s : (a) G e o l o g i c a l Survey of Canada c o l l e c t i p r t < n o s . 24035, 24040, and 24041; at latitude\69y ° 0 3 ' , l o n g i t u d e 130°21"; 3.0 miles S 30° E from Veronica Lake near milepost 702 A l a s k a High way. F o s s i l s were c o l l e c t e d from Lord's Group C sediments, and (b) G e o l o g i c a l Survey of Canada c o l l e c t i o n no. 24036; at l a t i t u d e 60°12 ' 30" , l o n g i t u d e 1 3 1 o l l ' 3 0 " ; 1.0 m i l e due northeast from northeast end of Crescent Lake. F o s s i l s were c o l l e c t e d from Lord's Group B sediments. D e t a i l e d s t r a t i g r a p h y of the f o s s i l l o c a l i t i e s i s not immediately a v a i l a b l e , but Poole r e p o r t s that the f o s s i l s occur i n carbonate rocks of Lord's (1944) Group B and Group C sediments. Lord, doing e a r l i e r g e o l o g i c a l reconnaissance work i n t h i s area f o r the G e o l o g i c a l Survey of Canada, devised a t a b l e of formation shown i n Table 1. Era P e r i o d L i t h o l o g y Cenozoic T e r t i a r y ? B a s a l t Mesozoic J u r a s s i c or l a t e r G r a n i t e , g r a n o d i o r i t e , and a l l i e d rocks; u n d i f f e r e n t  i a t e d s c h i s t and gneiss P e r i d O t i t e and d u n i t e ; serpentine J u r a s s i c (?) Group D: t u f f , a n d e s i t e , agglomerate, a r g i l l i t e , and s c h i s t Palaeozoic C a r b o n i f e r  ous (?) Group C: limestone, dolomite, a r g i l l i t e , s l a t e , p h y l l i t e , q u a r t z i t e , and s c h i s t Palaeozoic (?) Group B: a r g i l l i t e , s l a t e , p h y l l i t e , c h e r t , q u a r t z i t e , arkose, conglomerate, and limestone Palaeozoic and/or Pre- Cambrian Group A: g n e i s s , s c h i s t , limestone, d o l o m i t e , quartz i t e , and greenstone Table 1. Table of Formations 15 Lord (1944) s t a t e s that the age of the highly- a l t e r e d and metamorphosed s t r a t a of Group C i s unknown, as no f o s s i l s were found i n them. He reports that rocks i n Group B con t a i n f o s s i l s suggestive of c r i n o i d stems, and the r e f o r e considered to be Palaeozoic (?) i n age. In Group C were found f o s s i l s i d e n t i f i e d as Lophophyllum ? cascadenses Warren ? and Hapsiphyllum cacareforme ( H a l l ) ? and a cup c o r a l too poorly preserved to be i d e n t i f i e d . On p a l a e o n t o l o g i c a l evidence, Lord suggests Group C belongs to the Carboniferous (?) p e r i o d . I t i s reported by him that Group B and Group C d i f f e r l i t h o l o g i c a l l y , but t h e i r r e l a t i v e age r e l a t i o n s h i p i s unknown because they are separated by the Ca s s i a r B a t h o l i t h . P r e p a r a t i o n and Study of F o s s i l s Most of the specimens were i n d i v i d u a l fragments,, but a number which were imbedded i n limestone blocks were cut out w i t h a diamond saw. Transverse and l o n g i t u d i n a l t h i n - s e c t i o n s , u s u a l l y taken from the upper p a r t , were made f o r a l l specimens except the h i g h l y fragmental ones. P o l i s h e d s e c t i o n s were made from a l l specimens. The specimens were f i r s t cut w i t h the saw, then ground smooth on a s t e e l l a p w i t h carborundum as the a b r a s i v e , and f i n a l l y p o l i s h e d on a cloth-covered l a p . 16 Dimensions of the specimens were c a r e f u l l y measured, e s p e c i a l l y the t o t a l diameter, diameter of the c e n t r a l c a v i t y , and the width of the i n t e r v a l l u m . The number of p a r i e t i e s (when regular ) at the measured diameter were counted and the p e r f o r a t i o n arrangements of the s k e l e t o n were determined from examinations of t h i n - s e c t i o n s . The i n t e r v a l l u m c o e f f i c i e n t , that i s , the r a t i o of the width of the i n t e r v a l l u m i n m i l l i m e t e r s to the diameter of the c e n t r a l c a v i t y i n m i l l i m e t e r s , and the p a r i e t a l c o e f f i c i e n t - the r a t i o of number of p a r i e t i e s to the diameter at whieh the p a r i e t i e s were counted - were c a l c u l a t e d . These co e f f i c i e n t s , along w i t h the nature of the inner and outer w a l l s and the i n t e r v a l l u m , were the main c r i t e r i a used t o c l a s s i f y the specimens. I t must be noted that the c o e f f i c i e n t s may be of d o u b t f u l value i n r a p i d l y expanding, i r r e g u l a r cups, i n which case, the general appearance becomes an important f a c t o r . Photographs of p o l i s h e d s e c t i o n s and n a t u r a l l y weathered out specimens were taken t o i l l u s t r a t e and supple ment the w r i t t e n d e s c r i p t i o n s . Thin-sections were used as negatives and p i c t u r e s were p r i n t e d d i r e c t l y from them. CHAPTER I I I SYSTEMATIC DESCRIPTIONS OF ARCHAEOCYATHA FROM THE YUKON Faunal L i s t PHYLUM ARCHAEOCYATHA CLASS ARCHAEOCYATHEA ORDER AJACICYATHIDA Family A j a c i c y a t h i d a e Ajacicyathus p u r c e l l e n s i s O k u l i t c h A j a c i c y a t h u s yukonensis n. sp. Family Ethmophyllidae Ethmocoscinus sp. Family Coseinocyathidete Coscinocyathus dentocahis O k u l i t c h Coscinocyathus multiporus n. sp. Coscinocyathus c a s s i a r i e n s i s n. sp. Coscinocyathus i n e q u i v a l i u s n. sp. Coscinocyathus s e r r a t u s n. sp. Coscinocyathus veronicus n. sp. Coscinocyathus tubicornus n. sp. Coscinocyathus sp. Carinacyathus perfqratus n. sp. ORDER METACYATHIDA Family Archaeocyathidae Archaeocyathus c f . a t l a n t i c u s B i l l i n g s Archaeocyathus (?) sp. 18 Family Pycnoidocyathidae Pycnoidocyathus amourensis ( O k u l i t c h ) Pycnoidocyathus columbianus ( O k u l i t c h ) Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) Pcynoidocyathus c f . d i s s e p i m e n t a l i s ( O k u l i t c h ) Pycnoidocyathus s o l i d u s n. sp. Loculicyathus e l l i p t i c u s n. sp. Family Metacoscinidae Metacoscinus poolensls n. sp. Metacoscinus sp. Claruscyathus ketzaensis n. sp. The above l i s t i n c ludes archaeocyathids of both c o l l e c t i o n s . In the f o l l o w i n g d e s c r i p t i o n of s p e c i e s , f o s s i l s c o l l e c t e d by Aho and Padgham are designated by l e t t e r s "AP" and the specimen number. F o s s i l s from the Ge o l o g i c a l Survey of Canada c o l l e c t i o n are marked w i t h the l e t t e r "Y" preceded by a two d i g i t number and followed by the specimen number, f o r example, 35-Y-l. The f i r s t number i s taken from the l a s t two d i g i t s of the G e o l o g i c a l Survey of Canada c o l l e c t i o n number, 24035, and 1 i s the specimen number of that c o l l e c t i o n . D e s c r i p t i o n of Species Order AJACICYATHIDA Bedford and Bedford, 1939 Family A j a c i c y a t h i d a e Bedford and Bedford, 1939 19 A jacicyathus p u r c e l l e n s i s O k u l i t c h P l a t e I ; F i g . 1 Ajacicya t h u s p u r c e l l e n s i s O k u l i t c h , 1947 D e s c r i p t i o n General Shape and S i z e This i s a common species found i n the Lower Cam b r i a n formations of the northern C o r d i l l e r a n r e g i o n . The specimens from the Wolf Lake Area, Yukon are short fragments of a form o r i g i n a l l y g e n t l y tapered and c o n i c a l w i t h a n a t u r a l l y e l l i p t i c a l c r o s s - s e c t i o n . The f o l l o w i n g are the average dimensions taken from four specimens: Diameter 2 5 mm. Diameter of c e n t r a l c a v i t y 16 mm. Width of i n t e r v a l l u m 6 mm. Number of p a r i e t i e s 73 Int e r v a l l u m c o e f f i c i e n t 0.38 P a r i e t a l c o e f f i c i e n t 2.92 Outer W a l l The outer w a l l i s t h i n , simple, and perforated by numerous f i n e pores, about 3 or 4 per i n t e r s e p t . I n t e r v a l l u m The medium wide i n t e r v a l l u m i s crossed by a moderate number of s t r a i g h t , r a d i a t i n g p a r i e t i e s . P a r i e t i e s , spaced about 1 mm. a p a r t , are t h i n , s imple, and per f o r a t e d by a number of small pores. Inner W a l l The inner w a l l appears simple and perfo r a t e d by pores, about 2 to 3 per i n t e r s e p t . In a l l specimens examined, 20 the inner wall and parts of the intervallum are replaced by c a l c i t e . Thus much of the pore arrangements are ob l i t e r a t e d . C o l l e c t i o n Geological Survey of Canada, c o l l e c t i o n no. 24035 Specimen nos. 35-Y-5» 6» 7 and 8 . Collected by W.H. Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. Discussion The specimens of A.lacicyathus purcellensis Okulitch from the Yukon are almost i d e n t i c a l i n c h a r a c t e r i s t i c s to those found i n the Donald formation of the Dogtooth Mountains and i n the Upper Wolverine complex of Aiken Lake Area. No addition or amendments can be made to the o r i g i n a l description. A.lacicyathus yukonensis n. sp. Plate I ; F i g . 2 Description General Shape and Size Description of this species Is based on a single specimen from which a transverse thin-section was prepared, c and appears on the same glass s l i d e as Cos^nocyathus  multiporus n. sp. It i s a r e l a t i v e l y small conical form which i s s l i g h t l y e l l i p t i c a l i n transverse section. 21 Diameter 7 -9 mm. Diameter of c e n t r a l c a v i t y . . . . 3 . 2 mm. Width of i n t e r v a l l u m 2 - 2 ^ mm. Number of p a r i e t i e s 17 I n t e r v a l l u m c o e f f i c i e n t 0 . 7 1 P a r i e t a l c o e f f i c i e n t 2 . 2 1 Outer Wall The outer w a l l i s t h i n , simple, and perforated by numerous s m a l l pores, up to s i x per i n t e r s e p t . The c l o s e l y spaced f i n e pores give the w a l l , i n c r o s s - s e c t i o n , a minute " r i p p l y " c h a i n - l i k e appearance. S t i r r u p pores are l o c a t e d along the i n t e r s e c t i o n of the p a r i e t i e s w i t h the outer w a l l . I n t e r v a l l u m The i n t e r v a l l u m i s r e l a t i v e l y wide and crossed by seventeen s t r a i g h t , r a d i a t i n g p a r i e t i e s of which two are s h o r t , incomplete, and i n t e r s t i t i a l . The p a r i e t i e s appear to be imperforated, but may have pores near the inner w a l l . Thickening of the p a r i e t i e s occurs where they j o i n the outer w a l l and a l s o s l i g h t t h i c k e n i n g occurs at the inner w a l l . Inner Wall The inner w a l l i s thickened and per f o r a t e d by pores i n a v e r t i c a l s e r i e s of about three per m i l l i m e t e r . S t i r r u p pores appear t o be present. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 2 4 0 3 5 . Holotype i s specimen 35-Y-13 I-". C o l l e c t e d by W.H.Poole, 1 9 5 3 . 22 Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments), Wolf Lake Area, Yukon. D i s c u s s i o n The wid e l y spaced, almost imperforated p a r i e t i e s and the pore arrangements of the w a l l s resemble Archaeocy- a t h e l l u s . but the l a c k of d i s t i n c t f l u t i n g s or furrows of the outer w a l l opposite the p a r i e t i e s and the l a r g e r s i z e undoubtedly place t h i s specimen w i t h A.lacicyathus. The wide i n t e r v a l l u m r e g i o n and low p a r i e t a l c o e f f i c i e n t of t h i s species are u n l i k e any known A.lacicyathus except p o s s i b l y f o r the l a r g e r A.lacicyathus khemtschikensis ( V o l o g d i n ) , but they d i f f e r i n the form of the l o c u l i . The low p a r i e t a l c o e f f i c i e n t of A.lacicyathus yukonensis n. sp. may not be of s p e c i f i c importance because recent i n v e s t i g a t i o n s made by Zhuravleva (1955) on the growth stages of A.lacicyathus  khemtschikensis (Vologdin) have revealed that at small d i a  meters, t h i s species has a very high p a r i e t a l c o e f f i c i e n t , but as the diameter i n c r e a s e s , the p a r i e t a l c o e f f i c i e n t de creases a c c o r d i n g l y . At a diameter of 2.0 mm. the p a r i e t a l c o e f f i c i e n t was found to be 5»5» at 4 . 5 mm., 4.0, and at 5.0 mm., diameter at m a t u r i t y , the p a r i e t a l c o e f f i c i e n t was 3.0. From t h i s she concludes that the c o e f f i c i e n t becomes constant only when the organism has reached m a t u r i t y ; t h e r e  f o r e , i t i s not a r e l i a b l e c r i t e r i o n to use i n i d e n t i f y i n g t h i s species i n the adolescent stages. This statement i s worth no t i n g because i t may be a p p l i c a b l e to other species but was not s t u d i e d on A.lacicyathus yukonensis n. sp. The pore patterns and the appearance of the i n t e r v a l l u m of the l a t t e r are s u f f i c i e n t l y d i s t i n c t from other species to j u s t i f y the new s p e c i e s . Family Ethmophyllidae O k u l i t c h , 1943 Ethmocoscinus (?) sp. P l a t e I ; F i g . 3 D e s c r i p t i o n General Shape and S i z e A s i n g l e , s u b c y l i n d r i c a l f o s s i l fragment w i t h an e l l i p t i c a l c r o s s - s e c t i o n i s noted i n t h i s c o l l e c t i o n . I t i s about 45 mm. long w i t h the lower p o r t i o n m i s s i n g . Diameter 19-22 mm. Diameter of c e n t r a l c a v i t y 4 mm. Width of i n t e r v a l l u m 8-8£ mm. Number of p a r i e t i e s 35 Spacing of -tabulae 1-6 mm. I n t e r v a l l u m c o e f f i c i e n t 2-2^ P a r i e t a l c o e f f i c i e n t 1.7 Outer Wall The outer w a l l of t h i s specimen i s r e l a t i v e l y t h i c k and p e r f o r a t e d by l a r g e pores, about 1 or 2 per i n t e r  sept. I n t e r v a l l u m The very wide i n t e r v a l l u m region i s crossed by i r r e g u l a r p a r i e t i e s which are perfo r a t e d by l a r g e pores and thickened near the inner w a l l . The i n t e r v a l l u m i s f u r t h e r occupied by porous tabulae spaced at i r r e g u l a r i n t e r v a l s . Inner V a i l The Ethmophyllum-type inner w a l l i s the most c h a r a c t e r i s t i c f e a t u r e of t h i s specimen. The inner w a l l i s wide and perfo r a t e d by very coarse oblique canals. In transverse s e c t i o n , these oblique canals appear as 3 or 4 rows of v e s i c u l a r tubes l i n i n g the inner w a l l . C o l l e c t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia; specimen no. AP 7. C o l l e c t e d by Aho and Padgham, 1955. Horizon and L o c a l i t y Lower Cambrian limestones; P e l l y Mountains, Quiet Lake Area, Yukon. D i s c u s s i o n This specimen i s t e n t a t i v e l y placed i n the genus Ethmocoscinus because of the nature of the inner w a l l and the presence of tabulae i n the i n t e r v a l l u m . The very wide i n t e r v a l l u m and the much thickened, complicated v e s i c u l a r inner w a l l may warrant e r e c t i o n of a new genus, at l e a s t a new s p e c i e s , but u n t i l more specimens can be s t u d i e d to show that these c h a r a c t e r i s t i c s are d i s t i n c t and c o n s i s t e n t , such a c o n c l u s i o n would be premature. Family Coscinocyathidae T a y l o r , 1910 Coscinocyathus dentocanis O k u l i t c h P l a t e I ; F i g s . 4, 5 and 6 Coscinocyathus dentocanis O k u l i t c h , 1943 D e s c r i p t i o n This species i s very common i n the northern Cord- i l l e r a n province of North America and was f i r s t discovered i n the Dogtooth Range of P u r c e l l Mountains, B r i t i s h Columbia The o r i g i n a l d e s c r i p t i o n of the species by O k u l i t c h i s as f o l l o w s : The specimen i s a n a t u r a l l y weathered out l o n g i t u d i n a l s e c t i o n i n l i g h t - g r e y limestone. General Shape; Tubular, w i t h very s l i g h t t a p er. Reconstructed diameter must have been about 22 mm., and height about 60 or 70 mm., of which 50 mm. i s v i s i b l e . Width of i n t e r  vallum i s 5 mm. where diameter of c e n t r a l c a v i t y i s 12 mm., g i v i n g an i n t e r v a l l u m c o e f f i c i e n t of 5 mm. : 12 mm. Outer W a l l : Probably t h i n and simple. I n t e r v a l l u m : I n t e r v a l l u m i s crossed by r a d i a l v e r t i c a l p a r i e t i e s and s l i g h t l y convex upward tabulae. Resultant rectangular c e l l s or l o c u l i are about twice as high as wide; 14 p a r i e t i e s occur i n space of 1 cm., g i v i n g p a r i e t a l c o e f f i c i e n t of about 4 .5; tabulae are about 1 .5 mm. apart. Inner W a l l : Inner w a l l i s apparently smooth and simple, without any s t r u c t u r e s p r o j e c t i n g i n t o c e n t r a l c a v i t y . The specimens of t h i s c o l l e c t i o n agree c l o s e l y i n s p e c i f i c a t i o n s t o that of the o r i g i n a l except that the p a r i e t i e s may be s l i g h t l y t h i c k e r and fewer i n number at a 26 given diameter. The f o l l o w i n g measurements are the average taken from the present c o l l e c t i o n : Diameter 21-31 mm. Diameter of c e n t r a l c a v i t y . . . 11-19 mm. Width of i n t e r v a l l u m 5-7 mm. Number of p a r i e t i e s 90 Spacing of tabulae l£ mm. I n t e r v a l l u m c o e f f i c i e n t . . . . 0 . 4 P a r i e t a l c o e f f i c i e n t . 3 .46 The only a d d i t i o n which can be made to the o r i g i n a l d e s c r i p t i o n i s that Coscinocyathus dentocanis O k u l i t c h appears to be g e n e r a l l y e l l i p t i c a l i n c r o s s - s e c t i o n . The s m a l l d i f f e r e n c e s i n p a r i e t a l c o e f f i c i e n t are not considered to be of s p e c i f i c importance. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n nos. 24040 and 24041; specimen nos. 40-Y-4 and 611, and 41-Y-l. C o l l e c t e d by W.H. Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. Coscinocyathus multiporus n. sp. P l a t e I ; F i g s . 7, 8 and 9 D e s c r i p t i o n General Shape and S i z e This species i s based on a s i n g l e l a r g e specimen which was 118 mm. long before i t was cut. The. specimen i s p a r t i a l l y weathered away, thus exposing a l o n g i t u d i n a l 27 s e c t i o n which shows numerous tabulae c r o s s i n g the i n t e r  vallum. The f o s s i l i s shaped l i k e a l a r g e t a p e r i n g cone. Dimensions, taken 35 mm* down from the l a r g e r end, are only- approximate estimations because of the incomplete nature of the cup due to weathering. Diameter . 38 mm. Diameter of e e n t r a l c a v i t y . . . 16 mm. Width of i n t e r v a l l u m - 10 mm. Number of p a r i e t i e s 100 Spacing of tabulae 1-2 mm. In t e r v a l l u m c o e f f i c i e n t . . . . 0.63 P a r i e t a l c o e f f i c i e n t 2.63 Outer Wall The outer w a l l appears to be t h i n , s i m p l e , and pe r f o r a t e d by numerous pores, about 2 t o 4 per i n t e r s e p t . I n t e r v a l l u m The i n t e r v a l l u m of the upper p o r t i o n of the specimen i s r e l a t i v e l y wide w i t h an i n t e r v a l l u m c o e f f i c i e n t of 0 .63, but i n the lower r e g i o n s , the i n t e r v a l l u m becomes extremely wide w i t h i t s r a t i o to the c e n t r a l c a v i t y equal to 7s4 or 1.75. I t i s crossed by very porous p a r i e t i e s and tabulae. The p a r i e t i e s , many of which are the s h o r t , i n t e r s t i t i a l type growing i n from the outer w a l l , are t h i n , s t r a i g h t , r a d i a t i n g , and perforated by extremely f i n e pores c l o s e l y spaced. In a random c r o s s - s e c t i o n of a p a r i e t y , 22 or more may be present. Tabulae, a l s o p e r f o r a t e d by a great number of f i n e pores which produce a s i e v e - l i k e appearance, are e s s e n t i a l l y h o r i z o n t a l and r e g u l a r i l y spaced about 1 to 2 mm. apart. Inner W a l l A s l i g h t l y o b l i q u e , l o n g i t u d i n a l t h i n s e c t i o n reveals c l e a r l y , the pore p a t t e r n of the inner w a l l . Large, o b l a t e , oval-shaped pores, which are as wide as the i n t e r  sept and occur, arranged i n a v e r t i c a l s e r i e s , 3 to 4 i n number w i t h i n the spacing of two tabulae, p e r f o r a t e the inner w a l l . The area of the v o i d i s , t h e r e f o r e , much greater than the area of the s o l i d . C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 2 4 0 3 5 . Holotype i s marked 3 5-Y - 1 3 I I C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The exceedingly numerous f i n e pores of the p a r i e t i e s and t a b u l a e , and the l a r g e pores of the inner w a l l are u n l i k e the porous nature of any p r e v i o u s l y described species. Because the s p i t z of t h i s specimen i s m i s s i n g , i t s nature i s not known, but the s m a l l e s t end present shows a very narrow c e n t r a l c a v i t y and a wide i n t e r v a l l u m crossed by very t h i c k and b i f u r c a t e d p a r i e t i e s . Coscinocyathus c a s s i a r i e s i s n. sp. P l a t e I ; F i g s . 1 0 , 1 1 , 12 and 13 D e s c r i p t i o n General Shape and S i z e These specimens, approximately 40 to 50 mm. In l e n g t h , are not complete archaeocyathids but are l o n g , t u b u l a r shaped fragments. They are e l l i p t i c a l i n c r o s s - s e c t i o n . Specimen no. 35-Y-7 i s taken as the holo- type w i t h dimensions as f o l l o w s : Diameter l5-20*jr mm. Diameter of c e n t r a l c a v i t y . . . 9-13 mm. Width of i n t e r v a l l u m 4 mm. Number of p a r i e t i e s 75 Spacing of tabulae 2 mm. or more In t e r v a l l u m c o e f f i c i e n t . . . . 0 . 3 6 P a r i e t a l c o e f f i c i e n t 4 . 1 5 The dimensions of no. 35-Y-9 are s l i g h t l y l a r g e r , but i t s c o e f f i c i e n t s are almost i d e n t i c a l w i t h those of the holotype. Although no. 35-Y-8 has a r e l a t i v e l y wide I n t e r v a l l u m , i t i s included i n t h i s group because i t i s s i m i l a r i n general appearance. Outer W a l l The outer w a l l i s not preserved; consequently, no accurate d e s c r i p t i o n can be given. I t i s p o s s i b l e that the w a l l was t h i n and simple. I n t e r v a l l u m The i n t e r v a l l u m i s crossed by numerous s t r a i g h t , r a d i a t i n g p a r i e t i e s and curved, n e t - l i k e tabulae. The 30 p a r i e t i e s may b i f u r c a t e , but are u s u a l l y r a d i a l , s t r a i g h t , and p e r f o r a t e d by many pores, up to ten i n a random c r o s s - s e c t i o n . The tabulae are arched, w i d e l y spaced, and per f o r a t e d by many coarse pores which produce a s i e v e - l i k e t e x t u r e . The l o n g i t u d i n a l s e c t i o n of no. 3 5-Y - 7 , showing s t r u c t u r e s b e t t e r than the ot h e r s , i s not q u i t e p a r a l l e l to the c e n t r a l a x i s of the specimen. This f a c t , combined w i t h the f a c t that the tabulae are not h o r i z o n t a l but d i p p i n g , accentuates the curved, i r r e g u l a r appearance of the tabulae. Inner W a l l The inner w a l l i s s l i g h t l y thickened and perfo r a t e d by l a r g e pores, about one to two per i n t e r s e p t . I n v e r t i c a l d i r e c t i o n , they are spaced approximately 0 . 7 to 0 . 8 mm. apart. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 2 4 0 3 5 . Holotype i s no. 3 5-Y - 7 ; paratypes are nos. 35-Y-8 and 9 . C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The porous nature, the t h i c k inner w a l l w i t h almost c a n a l - l i k e pores, and the i r r e g u l a r , curved tabulae of t h i s species d i s t i n g u i s h i t from other Coscinocyathus. Coscinocyathus l n e q u l v a l i u s n. sp P l a t e I I ; F i g s . 1 , 2 , 3 , 4 , 5 and 6 . D e s c r i p t i o n General Shape and S i z e D e s c r i p t i o n i s based on s i x l o n g , c y l i n d r i c a l shaped specimens of which the longest was 45 mm. before i t was cut. The outer w a l l shows weak, r e g u l a r , t r a n s  verse annulations or c o n s t r i c t i o n s where i t i s j o i n e d by the tabulae. Dimensions are as f o l l o w s : Outer W a l l The outer w a l l i s simple and appears to be per f o r a t e d by l a r g e pores, but the pore p a t t e r n could not be determined. The w a l l i s s l i g h t l y c o n s t r i c t e d t r a n s v e r s a l l y at r e g u l a r i n t e r v a l s where i t i s jo i n e d by the tabulae. I n t e r v a l l u m The wide i n t e r v a l l u m r e g i o n i s crossed by p a r i e t i e s and tabulae. The p a r i e t i e s are t h i c k , s t r a i g h t , r a d i a t i n g , and perforated by small pores. Up to seven or e i g h t pores have been counted i n a random c r o s s - s e c t i o n of a p a r i e t y . A few p a r i e t i e s b i f u r c a t e towards the outer w a l l , and i n w e l l preserved specimens, they appear to extend a short 10-15 mm. 3-8 mm. 3£-5 mm. mm. distance i n t o the c e n t r a l c a v i t y . Very f i n e l y porous tabulae, which cross the i n t e r v a l l u m , are s l i g h t l y curved convex-upward, and are spaced about 1 to 2^ - mm. apart. The i n t e r s e c t i o n of tabulae w i t h p a r i e t i e s form rec t a n g u l a r l o c u l i of which the height, i n l o n g i t u d i n a l s e c t i o n , i s about 2 to 3 times the width. Inner W a l l L i k e the outer w a l l , the inner w a l l i s simple and perfor a t e d by l a r g e pores which appear t o be one per i n t e r  sept. However, p a r i e t i e s p r o j e c t a short distance from the inner w a l l i n t o the c e n t r a l c a v i t y , and i n t h i s r e  spect the inner w a l l d i f f e r s from the outer w a l l . C o l l e c t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia. No. AP-14 i s designated as the holotype; paratypes are nos. AP-13, 15, 16, 19, and 21. C o l l e c t e d by Aho and Padgham, 1955. Horizon and L o c a l i t y Lower Cambrian limestone from P e l l y Mountains, Quiet Lake Area, Yukon. D i s c u s s i o n The i n t e r v a l l u m and p a r i e t a l c o e f f i c i e n t s of t h i s species are almost i d e n t i c a l w i t h those of Coscinocyathus  equivallum T a y l o r . They d i f f e r , however, i n that the pores of t h i s species are much coarser and that the p a r i e t i e s 33 p r o j e c t i n t o the c e n t r a l c a v i t y making the inner w a l l d i s s i m i l a r i n appearance to the outer w a l l , hence the name Coscinocyathus i n e q u i v a l l u s as opposed to CoscInocyathus  equlvallum T a y l o r . The general appearance of Coscinocyathus i n e q u i v a l l u s n. sp. c l o s e l y resembles Coscinocyathus dentocanis O k u l i t c h , but i s much sm a l l e r . The width of the i n t e r v a l l u m t o the diameter of the c e n t r a l c a v i t y r a t i o i s much l a r g e r , and the p a r i e t i e s appear to be t h i c k e r i n t h i s s p e c i e s . O k u l i t c h (1948) has described a Coscinocyathus sp. from the Dogtooth Range of B r i t i s h Columbia as f o l l o w s : I t i s an a c u t e l y c o n i c a l fragment exposing a pleosponge i n a n a t u r a l l o n g i t u d i n a l s e c t i o n . The specimen i s e n t i r e l y r e c r y s t a l l i z e d and no d e t a i l s of i t s s t r u c t u r e , except a few upward arching tabulae, are v i s i b l e . The i n t e r v a l l u m c o e f f i c i e n t i s 4:6 or 0.6; the tabulae are spaced from l*js- mm. to 2 mm. apart. The t o t a l l e n g t h of the specimen i s 40 mm. and the maximum diameter i s 14 mm. An exposed p o r t i o n of the inner w a l l i n d i s t i n c t l y shows numerous, crowded, very f i n e pores. The outer w a l l i s worn smooth and does not show the pores. In one p o r t i o n of the specimen are f a i n t l y v i s i b l e t h i n s t r a i g h t p a r i e t i e s spaced about one-third of a m i l l i m e t e r apart. The poor p r e s e r v a t i o n of the specimen does not permit i t s s p e c i f i c determination beyond the f a c t that i t i s a Coscinocyathus w i t h elongated rect a n g u l a r l o c u l i . This d e s c r i p t i o n seems to f i t c l o s e l y , except p o s s i b l y f o r the inner w a l l , that of Coscinocyathus i n e q u i v a l l u s n. sp. U n t i l b e t t e r specimens can be found i n the Donald Formation of the Dogtooth Range, or other 34 l o c a l i t i e s , no d e f i n i t e c o n c l u s i o n can be made as to whether Coscinocyathus i n e q u i v a l l u s n. sp. i s a wid e l y d i s t r i b u t e d s p e c i e s . Coscinocyathus s e r r a t u s n. sp. P l a t e I I ; F i g s . 7 and 9 D e s c r i p t i o n General Shape and S i z e D e s c r i p t i o n i s based on a s i n g l e specimen, AP - 1 7 , which was about 50 mm. i n l e n g t h before i t was cut. I t i s a fragment of an acute c o n i c a l cup w i t h a s l i g h t l y e l l i p t i c a l c r o s s - s e c t i o n . The diameters of the lower, middle, and upper parts are 18, 2 3 , and 28 mm., r e s p e c t i v e l y . Weak, transverse annulations of the outer w a l l , s i m i l a r to those of Coscinocyathus i n e q u i v a l l u m n. sp., are present. Complete dimensions of the upper, middle, and lower p o r t i o n s are as f o l l o w s : Upper Middle Lower Diameter 28 mm. 23 mm. 18 mm. Diameter of c e n t r a l c a v i t y . . . . 15 mm. 10 mm. 8 mm. Width of i n t e r v a l l u m 7-8 mm. 7 mm. 5 mm. Number of p a r i e t i e s 105 80 70 Spacing of tabulae 3 -3£ mm. 3 - 3 ? mm. 3-3*r mm. In t e r v a l l u m c o e f f i c i e n t 0 . 5 0 . 7 0 . 6 3 P a r i e t a l c o e f f i c i e n t . . . . . . . 3 . 7 5 3 . 5 3 . 9 Outer W a l l Much of the outer w a l l has been replaced by c a l c i t e , but i t appears to be t h i n , s i m p l e , and pe r f o r a t e d by l a r g e 35 pores. Pore arrangement could not be determined. I n t e r v a l l u m The r e l a t i v e l y wide i n t e r v a l l u m r e g i o n i s crossed by a number of s t r a i g h t , r a d i a t i n g p a r i e t i e s which are per f o r a t e d by a few small pores. An o c c a s i o n a l p a r i e t y may b i f u r c a t e . Up-arching t a b u l a e , p e r f o r a t e d by numerous sm a l l c i r c u l a r pores, crossed the i n t e r v a l l u m at r e l a t i v e l y w i d e l y spaced i n t e r v a l s . Inner W a l l The c h a r a c t e r i s t i c f e a t u r e of t h i s species i s i t s inner w a l l . In transverse s e c t i o n , the inner w a l l , i n p a r t , appears t h i n , s imple, and perforated by sm a l l pores, but i n greater p a r t , appears complicated by hoo k - l i k e s t r u c t u r e s p r o j e c t i n g i n t o the c e n t r a l c a v i t y . In l o n g i t u d i n a l s e c t i o n , the hooked elements give the inner w a l l a s e r r a t e d appear ance. The inner w a l l s t r u c t u r e of t h i s species resembles that of Von T o l l ' s Archaeocyathus S i b l r i c u s and Taylor's Archaeocyathus W i r r i a l p e n s i s . G o l l e e t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia. Holotype i s specimen AP - 1 7 . C o l l e c t e d by Aho and Padgham, 1 9 5 5 . Horizon and L o c a l i t y Lower Cambrian limestone, P e l l y Mountains, Quiet Lake Area, Yukon. 36 D i s c u s s i o n S u p e r f i c i a l l y , t h i s species resembles Coscinocyathus  i n e q u l v a l l u s n. sp. and Coscinocyathus dentocanis O k u l i t c h , but i t Is much l a r g e r than the former. I t s w i d e l y spaced tabulae and complicated inner w a l l d i s t i n g u i s h i t from p r e v i o u s l y described species. Coscinocyathus veronicus n. sp. P l a t e I I ; F i g . 8 D e s c r i p t i o n General Shape and S i z e The shape of t h i s s p e c i e s , judged from a fragment about 40 mm. l o n g , i s that of a gen t l y t a p e r i n g cone. In c r o s s - s e c t i o n , i t has an e l l i p t i c a l o u t l i n e . Diameter 2 0 - 3 0 mm. Diameter of c e n t r a l c a v i t y . . . . 1 2 - 2 1 mm. Width of i n t e r v a l l u m 5 mm. Number of p a r i e t i e s 110 Spacing of tabulae 1-1? mm. Int e r v a l l u m c o e f f i c i e n t . . . . . 0 . 2 9 P a r i e t a l c o e f f i c i e n t 4.4 Outer W a l l The outer w a l l appears to be t h i n and simple; the pore p a t t e r n i s not c l e a r l y v i s i b l e . I n t e r v a l l u m The narrow i n t e r v a l l u m region i s crossed by s t r a i g h t , r a d i a t i n g p a r i e t i e s and c l o s e l y spaced, f i n e l y porous tabulae. The p a r i e t i e s are perfo r a t e d by a few f i n e pores and thickened by secondary c a l c i t e . L o c u l i are r e c t a n g u l a r , s l i g h t l y higher than wide. Inner W a l l The inner w a l l , p e r f o r a t e d by r e l a t i v e l y l a r g e pores, appears to be very t h i n and simple. Because the specimen i s not w e l l preserved, the pore p a t t e r n could not be determined. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n nos. 24040 and 24041. Holotype i s marked 40-Y-2; paratypes are 41-Y-2 and 4. C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n This species i s s i m i l a r i n p a r i e t a l c o e f f i c i e n t to Coscinocyathus dentocanis O k u l i t c h , but d i f f e r s i n the i n t e r v a l l u m c o e f f i c i e n t and i n the spacing of the tabulae. The almost quadrate l o c u l i of t h i s species resembles those of Coscinocyathus rhyacoensis O k u l i t c h and Coscinocyathus  quadratus Bedford and Bedford, but the new species d i f f e r s from the l a t t e r two i n the c o e f f i c i e n t s . 38 Coscinocyathus tubicornus n. sp. P l a t e I I ; F i g s . 10 and 11. D e s c r i p t i o n General Shape and S i z e This species i s represented by a s i n g l e specimen, a s l i g h t l y curved t u b u l a r form p a r t i a l l y weathered out. I t s diameter decreases from 21 t o 12 mm, i n a l e n g t h of 60 mm. The lower p o r t i o n i s missing on t h i s specimen. I t i s r e  placed to some extent by c a l c i t e , which o b l i t e r a t e s the f i n e r d e t a i l s of the s k e l e t o n . Diameter 21-22 mm. Diameter of c e n t r a l c a v i t y . . . . 8-9 mm. Width of i n t e r v a l l u m . . . . . . . 6-7 mm. Number of p a r i e t i e s 80 Spacing of tabulae 1-^ -2 mm. In t e r v a l l u m c o e f f i c i e n t 0.77 P a r i e t a l c o e f f i c i e n t 3.81 Outer W a l l The outer w a l l appears t h i n and simple. The pore p a t t e r n cannot be determined from t h i s specimen. I n t e r v a l l u m The wide i n t e r v a l l u m i s crossed by p a r i e t i e s and tabulae. The p a r i e t i e s are t h i n , s t r a i g h t , r a d i a t i n g , and per f o r a t e d by numerous f i n e pores. Tabulae, spaced about l£ t o 2 mm. ap a r t , are porous mesh-like and s l i g h t l y arched convex-upward. Inner W a l l The inner w a l l i s very t h i n , simple, and per f o r a t e d by p o s s i b l y two pores per i n t e r s e p t . The exact pore 39 arrangement of the inner w a l l i s not known. In p a r t , the w a l l appears to be invaded and pushed i n by f o r e i g n m a t e r i a l , causing the p a r i e t i e s to p r o j e c t s l i g h t l y i n t o the c e n t r a l c a v i t y . C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24036. Holotype i s marked 3 6 - Y - l l . C o l l e c t e d by W.H. Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group B sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The t h i n , simple, r a d i a t i n g p a r i e t i e s and c l o s e l y set tabulae of t h i s specimen place i t i n the genus Coscinocyathus. However, the wide i n t e r v a l l u m , the narrow c e n t r a l c a v i t y , and i n the main, the general appearance of t h i s species are qu i t e d i f f e r e n t from those of the other s p e c i e s . Coscinocyathus c y l i n d r i c u s Boremann and Coscin  ocyathus tuba Bornemann a l s o have a wide i n t e r v a l l u m , but i n general appearance, t h i s new species i s q u i t e unique. Coscinocyathus sp. P l a t e I I ; F i g . 12 D e s c r i p t i o n General Shape and S i z e This species i s represented by a very short f r a g -40 ment of a long c y l i n d r i c a l form. Because i t s general appearance i s not known and much of the f o s s i l i s replaced by e a l c i t e , a s p e c i f i c determination can not be made. Diameter . . . . . 25-32 mm. Diameter of c e n t r a l c a v i t y . . . . 15 mm. Width of i n t e r v a l l u m 5-9 mm. Number of p a r i e t i e s . . . . . . . . 106 Spacing of tabulae 1-1?^ mm. In t e r v a l l u m c o e f f i c i e n t 0.4? P a r i e t a l c o e f f i c i e n t 3.72 Outer W a l l The outer w a l l i s a simple t h i n mesh, perforated by f i n e pores. I n t e r v a l l u m Extremely t h i n , r a d i a t i n g p a r i e t i e s p e r f o r a t e d by very f i n e pores, and f l a t , c l o s e l y spaced, n e t - l i k e tabulae cross the i n t e r v a l l u m r e g i o n . Inner Wall The inner w a l l appears very t h i n and p o s s i b l y per f o r a t e d by numerous f i n e pores. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24036. Specimen i s marked 36-Y-10. C o l l e c t e d by W.H.Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group B sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The general appearance and the s a l i e n t features 41 can not be determined on t h i s s m a l l fragment, but the very t h i n and d e l i c a t e nature of the w a l l s and s k e l e t a l elements i s the s t r i k i n g c h a r a c t e r i s t i c . The fineness of the s k e l e t o n resembles that of Coscinocyathus tubicornus n. sp. but i t d i f f e r s i n i n t e r v a l l u m c o e f f i c i e n t . I f other specimens of the former can be found to show that l a r g e r diameters give smaller i n t e r v a l l u m c o e f f i c i e n t s , then the specimen under c o n s i d e r a t i o n could c e r t a i n l y be c l a s s i f i e d as Coscinocyathus  tubicornus n. sp. The c o e f f i c i e n t s of t h i s specimen are s i m i l a r to those of Coscinocyathus dentocanis O k u l i t c h , but i n general appearance there seems to be no resemblance. Carinacyathus perforatus n. sp. P l a t e I I I ; F i g s . 1-5 D e s c r i p t i o n General Shape and S i z e N a t u r a l l y weathered out specimens of t h i s species were up to 110 mm. long and t u b u l a r i n shape before they were cut. In c r o s s - s e c t i o n , they are e l l i p t i c a l . Specimen 35-Y-12, being the best preserved, was chosen as the holotype. 42 Diameter 2 1 - 3 5 mm. Diameter of c e n t r a l c a v i t y . . . . 16 mm. Width of i n t e r v a l l u m . . 4-8 mm. Number of p a r i e t i e s . 100 Spacing of tabulae l ^ - 2 j | mm. In t e r v a l l u m c o e f f i c i e n t 0 . 3 8 P a r i e t a l c o e f f i c i e n t 3 . 5 7 Outer W a l l The outer w a l l i s not w e l l preserved, but appears to be t h i n , s imple, and perfo r a t e d by numerous sm a l l pores. The pore p a t t e r n i s not known. In t e r v a l l u m The i n t e r v a l l u m i s crossed by numerous s t r a i g h t , r a d i a t i n g p a r i e t i e s and by weakly up-arched tabulae. The p a r i e t i e s , spaced about 0 . 8 mm. a p a r t , are p e r f o r a t e d , i n a random c r o s s - s e c t i o n , by twelve or more very f i n e pores about 0.1 mm. i n diameter. The t a b u l a e , spaced l£ t o 2-jj? mm. apar t , are perfo r a t e d by numerous f i n e pores, r e s u l t i n g i n a f i n e meshed net. The i n t e r s e c t i o n of tabulae w i t h p a r i e t i e s form rectangular l o c u l i , which are about twice as high as they are wide. Inner W a l l The most c h a r a c t e r i s t i c f e a t u r e of t h i s species i s i t s inner w a l l . I t i s composed of continuous annular, s i g m o i d a l l y curved p l a t e s spaced about 0 . 5 mm. apart i n l o n g i t u d i n a l d i r e c t i o n . They p r o j e c t about 0 . 3 to 0.4 mm. i n t o the c e n t r a l c a v i t y and l i n e i t w i t h h o r i z o n t a l annular s h e l v e s . 43 C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24035. Holotype i s no. 35-Y-12; paratypes are nos. 35-Y-6 and 10. C o l l e c t e d by W.H.Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n These specimens, w i t h w e l l developed tabulae and s t r a i g h t , r a d i a t i n g p a r i e t i e s , undoubtedly belong to the f a m i l y Coscinocyathidae Taylor and are c l a s s i f i e d as genus Carin<jcyathus V o l o g d i n because of t h e i r complex inner w a l l . The Bedfords (1936a) have described a new genus Sigmocoscinus w i t h Sigmocoscinus sigma Bedford and Bedford as genotype. The c o e f f i c i e n t s and d e s c r i p t i o n of the s k e l e t a l s t r u c t u r e , except f o r the outer w a l l , c l o s e l y resemble those of Carinacyathus p e r f o r a t u s n. sp. The outer w a l l of Sigmocoscinus sigma i s described as fol l o w s by Bedford and Bedford, outer wall-pores are s m a l l , about 4 to one mm., about three rows t o each i n t e r s e p t , and are covered e x t e r n a l l y by overlapping annular p l a t e s , about 4 of these o c c u r r i n g i n each mm. of l e n g t h . An outer w a l l , composed of sigmoidal annular p l a t e s , i s , not present on these specimens, perhaps the r e s u l t of poor p r e s e r v a t i o n . I f t h i s i s the case, then the f o s s i l s here described are Sigmocoscinus sigma. Since the term Sigmocoscinus i s not l i s t e d i n T r e a t i s e Of Invertebrate Paleontology. Part E by O k u l i t c h , i t i s considered as an i n v a l i d name. Genus Carinacyathus i n c l u d e s a l l Coscinocyathidae w i t h complex inner w a l l s , i r r e s p e c t i v e of the nature of the outer w a l l . Hence, i f b e t t e r specimens can be found from the same l o c a l i t y to prove that these specimens are c o n s p e c i f i c w i t h Sigmoco scinus sigma. then they should be c l a s s e d as Carinacyathus  sigma (Bedford and Bedford). Carinacyathus p e r f o r a t e s n.sp. c l o s e l y resembles Coscinocyathus dentocanis O k u l i t c h but i t d i f f e r s i n the nature of the inner w a l l . Specimen no. 35-Y-10 i s s i m i l a r to the holotype, except that i t has a l a r g e r c e n t r a l c a v i t y . The inner w a l l i s complicated by elements p r o j e c t i n g i n t o the c a v i t y r e g i o n , but the arrangement i s not c l e a r l y v i s i b l e ; there fo r e specimen 35-Y-10 i s p r o v i s i o n a l l y c l a s s e d as Carinacyathus perforatus n. sp. Occurrences of t h i s genus have been reported from S i b e r i a and A u s t r a l i a but t h i s i s i t s f i r s t occurrence i n North America. 45 Order METACYATHIDA Bedford and Bedford, 1936 Family Archaeocyathidae T a y l o r , 1910 Archaeocyathus c f , a t l a n t i c u s B i l l i n g s P l a t e I I I ; F i g s . 6 and 7 Archaeocyathus a t l a n t i c u s B i l l i n g s , 1861 D e s c r i p t i o n General Shape and S i z e The specimen i s a l a r g e , f l a t t e n e d archaeocyathid about 135 mm. long. I t i s conceivable that i t was o r i g i n a l l y l o n g , acute c o n i c a l i n form w i t h an e l l i p t i c a l c r o s s - s e c t i o n . Because of extreme deformation and the p a r t i a l l y weathered away c o n d i t i o n at the upper end, dimensions are only estimates. Upper Lower Diameter 44 mm. 30 mm. Diameter of c e n t r a l c a v i t y . . . 15-16 mm. 9 mm. Width of i n t e r v a l l u m 9-18 mm. 5-15 mm. Int e r v a l l u m c o e f f i c i e n t . . . . 0.87 0.94 Outer W a l l Due to replacement by c a l c i t e and to weathering away, the c h a r a c t e r i s t i c of the outer w a l l cannot be r e a d i l y seen. I t appears to be t h i n and d e l i c a t e , but no pore arrangements are known. In t e r v a l l u m The i n t e r v a l l u m i s r e l a t i v e l y wide w i t h an i n t e r -46 vallum c o e f f i c i e n t of about 0 . 9 , which i s i d e n t i c a l w i t h that of the o r i g i n a l G e o l o g i c a l Survey of Canada holotype no. 369 described by B i l l i n g s i n 1 8 6 1 . The i n t e r v a l l u m i s crossed, i n p a r t , by wavy p a r i e t i e s and, i n p a r t , by i r  r e g u l a r taeniae and s y n a p t i c u l a e . In the lower p o r t i o n s , taeniae are b i f u r c a t e d , anastomosed, and perforated by l a r g e pores, and appear to be thickened. Inner W a l l Poor p r e s e r v a t i o n makes i t impossible t o see the exact nature of the inner w a l l , but i t appears to be s l i g h t l y t h i c k e r than the outer w a l l . The pore p a t t e r n could not be determined. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24035* specimen no. 35-Y-14. C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n A d e f i n i t e i d e n t i f i c a t i o n cannot be made because of poor p r e s e r v a t i o n and extreme deformation of the o r i g i n a l general appearance. The i n t e r v a l l u m c o e f f i c i e n t and the i r r e g u l a r nature of the i n t e r v a l l u m s k e l e t a l elements of t h i s specimen resemble those of Archaeocyathus a t l a n t i c u s B i l l i n g s . U n t i l b e t t e r and more r e v e a l i n g specimens of t h i s archaeocyathid are made a v a i l a b l e , a new species w i l l not be erected here. Archaeocyathus (?) sp. P l a t e I I I ; F i g s . 8 D e s c r i p t i o n General Shape and S i z e This specimen i s a fragment about 30 mm. lo n g , of a l a r g e c o n i c a l shaped cup w i t h an e l l i p t i c a l cross s e c t i o n . I t i s cut by c a l c l t e s t r i n g e r s and much of the f o s s i l i s replaced by carbonate. Outer W a l l The outer w a l l appears t h i c k , s i m p l e , and p o s s i b l y p e r f o r a t e d by f i n e pores. I n t e r v a l l u m The i n t e r v a l l u m i s crossed by i r r e g u l a r b i f u r c a t i n g and anastomosing taeniae, and i n part by wavy Pyenoldo- eyathus-type p a r i e t i e s . P a r i e t i e s and taeniae are t h i c k and perfo r a t e d by l a r g e pores. Inner Wall The inner w a l l i s s l i g h t l y t h i c k e r than the outer w a l l , but the replacement by c a l c i t e makes the determination of the pore p a t t e r n impossible. Diameter Diameter of c e n t r a l c a v i t y . Width of i n t e r v a l l u m . . . . In t e r v a l l u m c o e f f i c i e n t . . 35-41 mm. 16-21 mm. 8-10 mm. 0.49 C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24041; specimen no. 41-Y-3. C o l l e c t e d by W.H.Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The i n t e r v a l l u m i s crossed i n part by t h i c k wavy p a r i e t i e s as found i n Pycnoidocyathus, and i n part by i r r e g u l a r taeniae c h a r a c t e r i s t i c of Archaeocyathus. In general appearance, the i n t e r v a l l u m , i n both transverse and l o n g i t u d i n a l view, resembles that of the l a t t e r . The c l a s s i f i c a t i o n , beyond the f a c t that i t belongs to the order Metacyathida, i s not d e f i n i t e and no s p e c i f i c deter mination i s p o s s i b l e from t h i s fragment. Family Pycnoidocyathidae O k u l i t c h , 1950 Pycnoidocyathus amourensis ( O k u l i t c h ) P l a t e IV ; F i g . 1 Cambrocyathus amourensis O k u l i t c h , 1943 D e s c r i p t i o n General Shape and S i z e In the Yukon c o l l e c t i o n s , t h i s common Labrador 49 species i s represented by a s i n g l e s m a l l fragment. The general shape cannot be determined from t h i s s m a l l p i e c e , but the dimensions are as f o l l o w s : Diameter 20 mm. Diameter of c e n t r a l c a v i t y . . . . 5 mm. Width of i n t e r v a l l u m 7 mm. Number of p a r i e t i e s 36 In t e r v a l l u m c o e f f i c i e n t 1.4 P a r i e t a l c o e f f i c i e n t 1.8 D i s c u s s i o n The s a l i e n t f e a t u r e s of the outer and inner w a l l s are o b l i t e r a t e d by c a l c i t e r e c r y s t a l l i z a t i o n . The narrow c e n t r a l c a v i t y and the nature of the i n t e r v a l l u m are d e f i n i t e l y r e l a t e d to Pycnoidocyathus amourensis ( O k u l i t c h ) but the general shape, which i s the main c r i t e r i o n used i n i d e n t i f i c a t i o n of t h i s s p e c i e s , i s not known f o r the specimen under d i s c u s s i o n . The low p a r i e t a l c o e f f i c i e n t i s not of s p e c i f i c importance because even i n the holotype, the co e f f i c i e n t v a r i e s to some extent at d i f f e r e n t diameters. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24036; specimen no. 36-Y-9. C o l l e c t e d by W.H.Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group B sediments); Wolf Lake Area, Yukon. Pycnoidocyathus columbianus ( O k u l i t c h ) P l a t e IV ; F i g . 2 50 Cambrqcyathus columbianus O k u l i t c h , 1943 D e s c r i p t i o n General Shape and S i z e D e s c r i p t i o n i s based on two specimens which are short fragments of l a r g e , c o n i c a l cups. Largest specimen i s about 70 mm. i n diameter and 60 mm. i n l e n g t h , which i s too short to show annulations of the outer w a l l . Diameter . . . . . . 65-70 mm. Diameter of c e n t r a l c a v i t y . . . . 34-36 mm. Width of i n t e r v a l l u m 16-18 mm. Number of p a r i e t i e s 90 I n t e r v a l l u m c o e f f i c i e n t 0.48 P a r i e t a l c o e f f i c i e n t 1.35 Outer W a l l The nature of the outer w a l l of these specimens are indeterminable because p a r i e t i e s d i f f u s e out i n t o the limestone matrix l e a v i n g no w a l l v i s i b l e . I n t e r v a l l u m The r e l a t i v e l y wide i n t e r v a l l u m i s crossed by numerous t h i n , wavy, perfo r a t e d p a r i e t i e s . R a d i a t i n g p a r i e t i e s , s u p p l i e d w i t h abundant s y n a p t i c u l a e , are s l i g h t l y thickened near the inner w a l l . Inner W a l l The inner w a l l i s s l i g h t l y thickened and pe r f o r a t e d by l a r g e pores but pore p a t t e r n could not be determined. Thickening of the inner w a l l and of the p a r i e t i e s where 51 they j o i n the inner w a l l may be due to replacement by c a l c i t e . C o l l e c t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia; specimens AP-22 and 23. C o l l e c t e d by Aho and Padgham, 1955. D i s c u s s i o n These specimens are i d e n t i f i e d as Pycnoidocyathus  columbianus ( O k u l i t c h ) on general appearance and i n t e r v a l l u m c h a r a c t e r i s t i c s . They are very s i m i l a r to Pycnoidocyathus columbianus from the McDame Area described by O k u l i t c h (1955). The McDame specimens have a f a i r l y constant i n t e r  vallum c o e f f i c i e n t between 0.41 and 0.45, hut the p a r i e t a l c o e f f i c i e n t i s q u i t e v a r i a b l e . Therefore, the low p a r i e t a l c o e f f i c i e n t of these specimens i s not of s p e c i f i c importance. These specimens are c l o s e l y r e l a t e d to Pycnoidocyathus o c c i d e n t a l i s ( O k u l i t c h ) i n s i z e and shape but the l a t t e r has a much higher i n t e r v a l l u m c o e f f i c i e n t . Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) P l a t e IV ; F i g s . 3,4,5 and 6 Cambrocyathus o c c i d e n t a l i s O k u l i t c h , 1943 D e s c r i p t i o n General Shape and S i z e This s p e c i e s , a l a r g e , c o n i c a l , expanding form, 52 i s represented i n the G e o l o g i c a l Survey of Canada C o l l e c t i o n by specimens approximately 130 mm. long. The lower p o r t i o n of the cone i s weakly to s t r o n g l y annulated t r a n s v e r s a l l y , but annulations are not prominent or are completely l a c k i n g i n the upper p a r t s . Dimensions of the l a r g e r end a r e , on the average, as f o l l o w s : Towards the apex of the cone, the diameter of the c e n t r a l c a v i t y , width of the i n t e r v a l l u m , and the number of p a r i e t i e s decrease correspondingly w i t h the decrease i n diameter of the outer cone. The transverse annulations of the w a l l s near the base cause some v a r i a t i o n s i n the co e f f i c i e n t s ; the i n t e r v a l l u m c o e f f i c i e n t s ranging from 0 . 6 0 to 1 . 0 w i t h an extreme case of 0 . 4 3 , and the p a r i e t a l co e f f i c i e n t s , from 1 .3 to 2 . 0 . Outer Wall The poor p r e s e r v a t i o n of the outer w a l l makes the determination of i t s pore p a t t e r n impossible. The outer w a l l i s t r a n s v e r s a l l y annulated at the s m a l l e r end of the cone. I n t e r v a l l u m The wide i n t e r v a l l u m i s crossed by wavy to b i f u r  c a t i n g p a r i e t i e s which are p e r f o r a t e d by numerous pores and s u p p l i e d w i t h abundant s y n a p t i c u l a e . P a r i e t i e s are r e l a t i v e l y thickened towards the inner w a l l . Diameter . Diameter of c e n t r a l c a v i t y . Width of i n t e r v a l l u m . . . . Number of p a r i e t i e s . . . . I n t e r v a l l u m c o e f f i c i e n t . . P a r i e t a l c o e f f i c i e n t . . . . 5 5 . 6 5 mm. 2 5 - 3 2 mm. 18 mm. 120 0 . 6 3 2 . 0 53 Inner Wall Near the upper end of the organism, the Inner w a l l appears t o be t h i n , s i m p l e , and perfo r a t e d by pores. Pore c h a r a c t e r i s t i c s could not be determined because of c a l c i t e replacement. In the lower end, the inner w a l l appears t o be complicated by i r r e g u l a r , transverse annulations and i s pe r f o r a t e d by numerous f i n e pores which give a ser r a t e d e f f e c t t o the w a l l i n random s e c t i o n s . C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24036. Specimen nos. 3 6 - Y - l , 2, 3, 4 and 12. C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group B sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The i n t e r v a l l u m and p a r i e t a l c o e f f i c i e n t s , s i z e , and general appearance of these specimens are almost i d e n t i c a l t o s p e c i f i c a t i o n s of the holotype described by O k u l i t c h (1943). Specimen no, 36-Y-3 of t h i s c o l l e c t i o n shows i r r e g u l a r i t i e s and numerous p e r f o r a t i o n s of the inner w a l l towards the smaller end but replacement by c a l c i t e o b l i t e r a t e s some of the f i n e r d e t a i l s . This species i s r e l a t e d to Pycnoidocyathus  columbianus ( O k u l i t c h ) but has a much l a r g e r i n t e r v a l l u m c o e f f i c i e n t . 54 Pycnoidocyathus c f . d i s s e p i m e n t a l i s ( O k u l i t c h ) P l a t e IV ; F i g . 7 Cambrocyathus d i s s e p i m e n t a l i s O k u l i t c h , 1943 D e s c r i p t i o n General Shape and S i z e True shape of the cup can not be given a c c u r a t e l y from the two fragments here d e s c r i b e d , but they appear t o be t a p e r i n g c o n i c a l cups. L o n g i t u d i n a l s e c t i o n s show very shallow transverse annulations of the outer w a l l . Diameter 35 mm. Diameter of c e n t r a l c a v i t y . . . . 14-16 mm. Width of i n t e r v a l l u m 7 -8 mm. Number of p a r i e t i e s 75 I n t e r v a l l u m c o e f f i c i e n t . . . . . 0 . 5 P a r i e t a l c o e f f i c i e n t 2.14 Outer Wall The outer w a l l i s not preserved. The outer w a l l of the holotype from Labrador Is described by O k u l i t c h (1943) as f o l l o w s : Outer W a l l : Of average t h i c k n e s s , penetrated by numerous f a i r l y l a r g e pores. Some of the pores open d i r e c t l y i n t o i n t e r p a r i e t a l spaces; others open i n t o oblique canals p e n e t r a t i n g w a l l at an angle. In some cases a c l u s t e r of pores appears to open i n t o same c a n a l . W a l l i s crenulated by transverse bulges, as i s t y p i c a l of the genus. Spacing of the bulges i s about 5 or 6 mm. Int e r v a l l u m The most c h a r a c t e r i s t i c f e a t u r e of t h i s species i s the i n t e r v a l l u m r e g i o n . I t i s completely f i l l e d w i t h d i s s e p i m e n t a l t i s s u e and s y n a p t i c u l a e , and i s crossed by r e l a t i v e l y t h i n , wavy r a d i a t i n g p a r i e t i e s which o c c a s i o n a l l y b i f u r c a t e . The p a r i e t i e s are very porous, w i t h eight or more pores v i s i b l e i n random cross s e c t i o n , and about seven i n f i v e m i l l i m e t e r s of a l o n g i t u d i n a l s e c t i o n . Inner W a l l In oblique s e c t i o n , the inner w a l l appears as a t h i n , f i n e l y porous mesh. No d e f i n i t e pore p a t t e r n could be seen i n these specimens, but i t appears i r r e g u l a r . C o l l e c t i o n Department of Geology, U n i t e r s i t y of B r i t i s h Columbia; specimen nos. AP-23 and 24. C o l l e c t e d by Aho and Padgham, 1955. D i s c u s s i o n These specimens are compared w i t h Pycnoidocyathus  d i s s e p i m e n t a l l s ( O k u l i t c h ) because of the dense t i s s u e f i l l i n g s of the i n t e r v a l l u m . The c o e f f i c i e n t s of these specimens are n e a r l y the same as that of the holotype, but p a r i e t i e s are thinner and more porous. These s l i g h t d i f f e r  ences may not be of s p e c i f i c importance to j u s t i f y e r e c t i o n of a new s p e c i e s . Pycnoidocyathus s o l i d u s n. sp. P l a t e IV ; F i g s . 8 and 9 D e s c r i p t i o n General Shape and S i z e D e s c r i p t i o n i s based on a s i n g l e specimen about 37 nim. long. The cup i s c o n i c a l i n shape, the l a r g e r end averaging 34 mm. i n diameter and the smaller end, 2 5 mm. The lower p o r t i o n of the cone i s miss i n g . The dimensions of the upper e l l i p t i c a l c r o s s - s e c t i o n are as f o l l o w s : Diameter 26V39 mm. Diameter of c e n t r a l c a v i t y . . . . 7 mm. Width of i n t e r v a l l u m 10-18 mm. Number of p a r i e t i e s 67 I n t e r v a l l u m c o e f f i c i e n t 2.0 P a r i e t a l c o e f f i c i e n t 1.97 Outer Wall The outer w a l l appears to be t h i n , simple, and perfor a t e d by one or two l a r g e pores per i n t e r s e p t . The w a l l s are thickened by c a l c i t e replacement. I n t e r v a l l u m The very wide i n t e r v a l l u m and the extremely narrow c e n t r a l c a v i t y are the most noteworthy features of t h i s s p e c i e s . The i n t e r v a l l u m i s crossed by r e l a t i v e l y t h i c k , wavy p a r i e t i e s which are penetrated by a few sm a l l pores. The p a r i e t i e s b i f u r c a t e and anostomose toward the outer w a l l but are s t r a i g h t and c l o s e l y crowded near the inner w a l l . They are sup p l i e d w i t h o c c a s i o n a l s y n a p t i c u l a e . Inner W a l l Another c h a r a c t e r i s t i c f e a t u r e of t h i s species i s i t s inner w a l l . At the l a r g e r diameter, the w a l l appears to be t h i n , simple, and p o s s i b l y perforated by sm a l l pores. Towards the base, the inner w a l l i s thickened c o n s i d e r a b l y and penetrated by l a r g e c a n a l - l i k e pores. The c e n t r a l c a v i t y here i s i n d e f i n a b l e because i t i s completely f i l l e d 57 w i t h i r r e g u l a r extraneous r o d - l i k e m a t e r i a l . C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24040. Holotype i s marked 40-Y-7. C o l l e c t e d by W.H. Poole, 1953. Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The generic c l a s s i f i c a t i o n of t h i s specimen i s un c e r t a i n because many of i t s features seem to resemble Pycnoidocyathus as w e l l as Metaldetes and Paranacyathus. The c e n t r a l c a v i t y , f i l l e d w i t h t r a b e c u l a r elements, shows a f f i n i t y to the l a s t two genera, but t h i s specimen i s c l a s s e d as Pycnoidocyathus because of i t s r e l a t i v e l y r e g u l a r but wavy p a r i e t i e s c h a r a c t e r i s t i c of t h i s s p e c i e s . Although no conclusions can be made here, there i s a p o s s i b i l i t y that e i t h e r or both Metaldetes and Paranacyathus could be classed w i t h the genus Pycnoidocyathus. The extremely wide i n t e r v a l l u m , narrow c e n t r a l c a v i t y which i s undefinable at the base, and the t h i c k wavy p a r i e t i e s are the main features of the sp e c i e s . The narrow c e n t r a l c a v i t y resembles that of Pycnoidocyathus amourensis ( O k u l i t c h ) but they d i f f e r r a d i c a l l y i n general appearance. 58 Loculicyathus e l l i p t i c u s n. sp. P l a t e V ; F i g s . 1 - 6 D e s c r i p t i o n General Shape and S i z e The specimens are t a p e r i n g , c o n i c a l cups about 60 to 70 mm. long on the average, but specimen no-* 35-Y-2 was 130 mm. i n l e n g t h before i t was cut. They are e l l i p t i c a l i n cross s e c t i o n . The average dimensions are: Diameter . . . . . 20 mm. Diameter of c e n t r a l c a v i t y . . . . 10-11 mm. Width of c e n t r a l c a v i t y 4Jr-5<jr mm. Number of p a r i e t i e s 55-65 I n t e r v a l l u m c o e f f i c i e n t 0.45-0.55 P a r i e t a l c o e f f i c i e n t . 2.75-3.25 Specimen 35-Y-2 i s much l a r g e r , but the diameter and c o e f f i c i e n t s taken at mid-point of l e n g t h are comparable to dimensions of the others. At the upper end of t h i s specimen, where the diameter i s 24 by 34 mm., the i n t e r  vallum i s very narrow, g i v i n g an i n t e r v a l l u m c o e f f i c i e n t of 4^:19 or 0.24. This v a r i a t i o n i s c o e f f i c i e n t , even w i t h i n a s i n g l e , l o n g , c o n i c a l specimen, throws doubt on the v a l i d  i t y of the c o e f f i c i e n t as a c r i t e r i o n f o r c l a s s i f y i n g s p e c i e s . Another p e c u l i a r feature of t h i s specimen i s that i n the upper region s , part of i t s i n t e r v a l l u m i s f i l l e d w i t h dense v e s i c u l a r t i s s u e w h i l e other parts are not. I t i s not known whether t h i s i s due to p r e s e r v a t i o n or to p a r a s i t i c or symbiotic a c t i v i t i e s . A l s o the bottom 20 mm. of t h i s specimen i s bent at r i g h t angles to the a x i s of the main cone, i n d i c a t i n g t h a t t h i s animal had a strange l i f e h i s t o r y . Outer W a l l Much of the outer w a l l i s worn away, but p o o r l y preserved parts i n d i c a t e a t h i n , s imple, p e r f o r a t e d w a l l . The pore p a t t e r n i s not known. Int a r v a l l u m The most c h a r a c t e r i s t i c f e a t u r e of t h i s species i s i t s i n t e r v a l l u m r e g i o n . I t i s crossed by c o a r s e l y p e r f o r a t e d , s t r a i g h t , r a d i a l p a r i e t i e s and i s completely f i l l e d w i t h v e s i c u l a r t i s s u e (except upper por t i o n s of 3 5-Y - 2 ) . V e s i c l e s are o b l i q u e l y elongated. The p a r i e t i e s can be seen d i s t i n c t l y even w i t h i n the v e s i c u l a r mass. Inner Wall The inner w a l l i s simple and has about the same thickness as the p a r i e t i e s . The w a l l i s p e r f o r a t e d by one or two coarse pores per i n t e r s e p t . C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 2 4 0 3 5 . Holotype i s 3 5 - Y - l ; paratypes are 3 5-Y - 2 , 3 , 4, 5 and 1 1 . C o l l e c t e d by W.H.Poole, 1 9 5 3 . D i s c u s s i o n Genus Loc u l i c y a t h u s was f i r s t found i n S i b e r i a and described by V o l o g d i n ( 1 9 3 D . These specimens are the f i r s t to be found outside of S i b e r i a and are d i f f e r e n t from 60 the S i b e r i a n s p e c i e s . In transverse s e c t i o n , Loculicyathus  e l l i p s i s n. sp. looks much l i k e Metacoscinus deasensis O k u l i t c h i n i t s c o a r s e l y p e r f o r a t e d r a d i a l w a l l s and i n t e r  vallum of dense v e s i c u l a r and diss e p i m e n t a l t i s s u e s . They d i f f e r i n that the former has no tabulae. Family Metacoscinidae Bedford and Bedford, 1932 Metacoscinus poolensis n. sp. P l a t e V ; F i g s . 7 - 11 D e s c r i p t i o n General Shape and S i z e This species i s represented by four l o n g , t a p e r i n g c o n i c a l fragments. They are e l l i p t i c a l i n c r o s s - s e c t i o n . The l a r g e s t fragment i s crenulated at the top and i s 45 mm. i n l e n g t h , but i t could e a s i l y have been two or three times as long. Diameter 28-34 mm. Diameter of c e n t r a l c a v i t y . . . . 14-20 mm. Width of i n t e r v a l l u m 8 mm. Number of p a r i e t i e s 80 Spacing of tabulae ^-"^s i m ' In t e r v a l l u m c o e f f i c i e n t 0.47 P a r i e t a l c o e f f i c i e n t 2.6 The above are average measurements of the l a r g e r end of the specimens. Towards the base, width of the i n t e r v a l l u m does not decrease correspondingly, g i v i n g a higher i n t e r v a l l u m c o e f f i c i e n t . 61 Outer Wall The outer w a l l i s marked w i t h g e n t l e , transverse annulations where the w a l l i s joined by the tabulae. The w a l l appears to be t h i n , d e l i c a t e , and p e r f o r a t e d by f i n e pores, up to s i x per i n t e r s e p t . The w a l l s being poorly preserved, exact determination of the pore p a t t e r n i s i mpossible. I n t e r v a l l u m The presence of t a b u l a e , p a r i e t i e s , and v e s i c u l a r t i s s u e s i s the c h a r a c t e r i s t i c f e a t u r e of the r e l a t i v e l y wide i n t e r v a l l u m r e g i o n . The p a r i e t i e s , s u p p l i e d w i t h few s y n a p t i c u l a e , are t h i n , s t r a i g h t , r a d i a t i n g and occas i o n a l l y b i r f u r c a t i n g . They seem to be almost Imperforated and to p r o j e c t a short distance i n t o the c e n t r a l c a v i t y . Tabulae, spaced about 1 to l«)r mm. a p a r t , are p e r f o r a t e d by extremely f i n e , c l o s e l y set pores. Towards the smaller diameter, the i n t e r v a l l u m r e g i o n becomes f i l l e d w i t h very f i n e v e s i c u l a r dissepimental t i s s u e . The upper regions and the c e n t r a l c a v i t y appear to be free of t h i s t i s s u e . Inner Wall Features of the inner w a l l are not c l e a r , but the w a l l appears to be invaded and pushed i n by f o r e i g n m a t e r i a l . The w a l l i s t h i n and p e r f o r a t e d by l a r g e pores which lead i n t o the l o c u l i . Very t h i n p a r i e t i e s p r o j e c t i n t o the c e n t r a l c a v i t y , but the c a v i t y i s f r e e of other elements. C o l l e c t i o n G e o l o g i c a l Survey of Canada; c o l l e c t i o n no. 24040. Holotype i s 40-Y - 5 ; paratypes are 4 0 - Y - l , 3 , and 6 1 1 . C o l l e c t e d by W.H.Poole, 1 9 5 3 . Horizon and L o c a l i t y Lower Cambrian (Lord's Group C sediments); Wolf Lake Area, Yukon. D i s c u s s i o n The r a d i a l p a r i e t i e s , t abulae, and v e s i c u l a r t i s s u e i n the i n t e r v a l l u m i n d i c a t e that these specimens belong to genus Metacoscinus, but the imperforated nature of the p a r i e t i e s i s not t y p i c a l of t h i s genus. This f a c t i s not considered to be of generic importance. This species resemble Metacoscinus deasensis O k u l i t c h , but d i f f e r s i n the nature of the p a r i e t i e s and the i n t e r v a l l u m c o e f f i c i e n t . The s p e c i f i c name i s proposed i n honour of Dr. Poole of the G e o l o g i c a l Survey of Canada. Metacoscinus sp. P l a t e V ; F i g . 12 D e s c r i p t i o n General Shape and S i z e This species i s represented by a s i n g l e p oorly preserved c o n i c a l fragment about 2 5 mm. long. Diameter 18 mm. Diameter of c e n t r a l c a v i t y . . . . 6 mm. Width of i n t e r v a l l u m 6 mm. Number of p a r i e t i e s 42 Spacing of tabulae ? In t e r v a l l u m c o e f f i c i e n t 1 .0 P a r i e t a l c o e f f i c i e n t 2.3 Outer W a l l The outer w a l l i s simple and pe r f o r a t e d by l a r g e pores. The pore p a t t e r n could not be determined. I n t e r v a l l u m The i n t e r v a l l u m w i d t h i s equal to the diameter of the c e n t r a l c a v i t y . The i n t e r v a l l u m i s crossed by r e g u l a r , wavy p a r i e t i e s which are perforated by pores and supported by s y n a p t i c u l a e . In transverse t h i n - s e c t i o n , porous tabulae can be seen, but the spacing of the tabulae could not be determined i n l o n g i t u d i n a l s e c t i o n . Inner Wall The inner w a l l Is simple, s l i g h t l y t hickened, and p e r f o r a t e d by l a r g e pores. The pore p a t t e r n i s not known. C o l l e c t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia; specimen no. AP-6. C o l l e c t e d by Aho and Padgham, 1955. Horizon and L o c a l i t y Lower Cambrian limestone; P e l l y Mountains, Quiet Lake Area, Yukon. D i s c u s s i o n This specimen i s p r o v i s i o n a l l y assigned to the genus Metacoscinus, but i t s s p e c i f i c name i s not determined. The p a r i e t a l and i n t e r v a l l u m c o e f f i c i e n t s are d i f f e r e n t from the c o e f f i c i e n t of known s p e c i e s . Claruscyathus ketzaensis n. sp. P l a t e V ; F i g s . 14 - 16 D e s c r i p t i o n General Shape and S i z e The specimens are s m a l l horn-shaped fragments, the l a r g e s t being about 35 mm. l o ng. The t i p s on some are s h a r p l y curved. Few show weak transverse a n n u l a t i o n s . The average measurements are: Diameter 18 mm. Diameter of c e n t r a l c a v i t y . . . . 5£ nim. Width of i n t e r v a l l u m &} mm. Number of p a r i e t i e s 40? Spacing of tabulae 1-2 mm. I n t e r v a l l u m c o e f f i c i e n t 1.2 P a r i e t a l c o e f f i c i e n t 2.4? Outer W a l l The outer w a l l i s r e l a t i v e l y t h i c k and p e r f o r a t e d by l a r g e canal-pores. The arrangement of the pores i s not known. I n t e r v a l l u m The very wide i n t e r v a l l u m region i s the most c h a r a c t e r i s t i c f e a t u r e of t h i s s p e c i e s , g i v i n g an i n t e r  vallum c o e f f i c i e n t of 1 . 2 . I t i s a l s o f i l l e d w i t h extremely coarse, curving and branching taeniae. These s t r u c t u r a l elements s t a r t out as p a r i e t i e s from the inner w a l l but break up i n t o i r r e g u l a r elements as they extend out i n t o the i n t e r v a l l u m . The i n t e r v a l l u m i s crossed by porous, up- arching tabulae 1 to 2 mm. apart. In l o n g i t u d i n a l s e c t i o n , the tabulae can be seen to depart h o r i z o n t a l l y from the i n n e r w a l l . The tabulae abut the outer w a l l at an acute angle. Inner W a l l The inner w a l l i s thickened c o n s i d e r a b l y and penetrated by coarse oblique pore-canals. In transverse s e c t i o n , the inner w a l l appearance approaches the v e s i c u l a r inner w a l l of Ethmophyllum. C o l l e c t i o n Department of Geology, U n i v e r s i t y of B r i t i s h Columbia. Specimen AP-2 i s designated as the holotype. Paratypes are AP - 1 , 3 , 4, 81, 811, 8 , 10 and 1 1 . C o l l e c t e d by Aho and Padgham, 1 9 5 5 . Horizon and L o c a l i t y Lower Cambrian limestone; P e l l y Mountains, Quiet Lake Area, Yukon. D i s c u s s i o n This species i s c l o s e l y r e l a t e d to Eucyathus obliquus O k u l i t c h from the Dogtooth Mountains, B.C. I t 66 d i f f e r s i n that the l a t t e r has Pycnoidocyathus-type p a r i e t i e s , w h i l e t h i s has i r r e g u l a r Archaeocyathus-type p a r i e t i e s . The s k e l e t a l s t r u c t u r e of Claruscyathus ketnaensis n.sp. i s unique. CHAPTER IV SUMMARY AND CONCLUSION A f f i n i t i e s To Other Faunae S i x f a m i l i e s , the A j a c i c y a t h i d a e , the Ethmophy- l l i d a e , the Coscinocyathidae, the Archaeocyathidae, the Pycnoidocyathidae, and the Metacoscinidae of the Phylum Arehaeocyatha are represented i n the f o s s i l c o l l e c t i o n s from the Yukon. In a l l , twenty-three s p e c i e s , of which twelve are new, are here described. The Yukon fauna i s dominated by Coscinocyathus and Pycnoidocyathus. The dominance of Coscinocyathus and Pycnoidocyathus, which i s c h a r a c t e r i s t i c of faunae to the south i n B r i t i s h Columbia, suggests that the Yukon fauna has a f f i n i t i e s w i t h the faunae i n B r i t i s h Columbia. The presence of Coscino cyathus dentocanis O k u l i t c h , Pycnoidocyathus columbianus O k u l i t c h , and A.lacicyathus p u r c e l l e n s i s O k u l i t c h shows c l o s e r e l a t i o n s h i p among the faunae. Metacoscinus, which i s a common genus i n the McDame c o l l e c t i o n , i s a l s o present i n the c o l l e c t i o n s s t u d i e d . The occurrence of Locu l i c y a t h u s  a n <^ Carinacyathus suggests r e l a t i o n s h i p between t h i s fauna and the S i b e r i a n and A u s t r a l i a n faunae. There appears to be a complete l a c k of r e l a t i o n s h i p between the Yukon fauna and the California-Nevada faunae, which are dominated by Ethmophyllidae. 68 I t was s u r p r i s i n g to f i n d a l a r g e number of new species i n the c o l l e c t i o n s . The f o s s i l l o c a l i t i e s i n the Yukon are only two to three hundred miles northwest of the McDame l o c a l i t y of B r i t i s h Columbia. S i m i l a r species were th e r e f o r e expected, but i n t h i s distance a great number of new species become present. Archaeocyathids are very abundant i n the Yukon and every new c o l l e c t i o n seems to produce new s p e c i e s . Age of the Rocks Archaeocyathids i n Lord's (1944) Groups B and C sediments d e f i n i t e l y date the rocks, i n p a r t , as upper Lower Cambrian. The r e l a t i v e age r e l a t i o n between Groups B and C was not known to Lord, but i t can now be asserted p o s i t i v e l y that both groups c o n t a i n f o s s i l i f e r o u s zones of the same age. The rock groups defined by Lord are l a r g e and may con t a i n a number of u n i t s . P o o r l y preserved f o s s i l s suggest i v e of c r i n o i d stems and cup c o r a l s were found i n Groups B and C sediments, r e s p e c t i v e l y . Lord, t h e r e f o r e , suggested that Group C may be of Carboniferous ? age. I t i s qu i t e p o s s i b l e that these l a r g e groups contain s t r a t a of d i f f e r e n t ages, c e r t a i n l y rocks of e a r l y Cambrian age. 69 Sedimentary rocks at the head waters of the Ketza R i v e r i n the P e l l y Mountains are a l s o of upper E a r l y Cambrian age. The r e g i o n a l geology of t h i s area i s l a r g e l y unknown, but the rocks here are probably a c o n t i n u a t i o n of the Lower Cambrian rocks exposed i n the Wolf Lake Area 120 miles to the southeast. I t i s apparent that a l a r g e area i n the Yukon i s u n d e r l a i n by Lower Cambrian Rocks. W e l l preserved Lower Cambrian archaeocyathids, O r d i v i c i a n g r a p t o l i t e s , and P a l a e o z o i c c o r a l s were c o l l e c t e d by H. T r e t t i n i n the P e l l y Mountains. These f o s s i l s were not studied i n d e t a i l , but they i n d i c a t e that good P a l a e o z o i c s e c t i o n s are present i n the Ketza R i v e r area. Suggestions f o r Further Studies Archaeocyathids from the Yukon are e x c e l l e n t m a t e r i a l f o r study because of t h e i r abundance and good p r e s e r v a t i o n . A systematic c o l l e c t i o n of archaeocyathids should be made i n conjunction w i t h d e t a i l e d s t r a t i g r a p h i c work and r e g i o n a l geology. I f p o s s i b l e , archaeocyathid f a u n a l zones should be erected. Further c o l l e c t i o n s from the Yukon w i l l undoubtedly f u r n i s h new s p e c i e s . B e t t e r specimens may provide a d d i t i o n a l i n f o r m a t i o n or amendments to the species of the present c o l l e c t i o n s . Studies on ecology, ontogony, and phylogeny of Arehaeocyatha are recommended i f l a r g e c o l l e c t i o n s of w e l l 70 preserved f o s s i l s can be made. Explanations for t h e i r sudden appearance and equally sudden extinction may then become apparent. BIBLIOGRAPHY Aho, A. ( 1955) Geologic Report on the Kay Group of Claims and Upper White Creek, Ketza R i v e r Area, Yukon T e r r i t o r y ; unpublished r e p o r t . Bedford, R. and Bedford, J . (1936) Further Notes on Cyathospongia from the Lower Cambrian of B e l t a n a , South A u s t r a l i a ; Kyancutta Museum Memoir 3 , pp. 21-26. (1937a) Anatomy and C l a s s  i f i c a t i o n of the Cyathospongia (Archaeos) from the Lower Cambrian of B e l t a n a , South A u s t r a l i a ? mimeographed copy, pp. 1-11. (1937b) Further Notes on Archaeos (Pleospongia) from the Lower Cambrian of South A u s t r a l i a ; Kyancutta Museum Memoir 4 , pp. 2 7 - 3 8 . (1939) Development and C l a s s  i f i c a t i o n of Archaeos (Pleospongia); Kyancutta Museum Memoir 6 , pp. 67-82. Bedford R. and Bedford W.R. (1934) New Species of Arehaeocyathinae and Other Organisms from the Lower Cambrian of B e l t a n a , South A u s t r a l i a ; Kyancutta Museum Memoir 1 , pp. 1 -7 . ( 1936) Further Notes on Arehaeocyathi (Cyathospongia) and Other Organisms from the Lower Cambrian of B e l t a n a , South A u s t r a l i a ; Kyancutta Museum Memoir 2 , pp. 9 - 2 0 . B i l l i n g s , E. (1865) P a l e o z o i c F o s s i l s ; Geol. Survey of Can., v o l . 1 , pp. 3 - 6 , 3 5 4 - 3 5 7 , 419. C h i , Y.S. (1940) Cambrian Archaeocyathina from the Gorge D i s t r i c t of the Yangtze; Geol. Soc. China, B u l l . , v o l . 2 0 , no. 2 , pp. 121-142. Ford, S.W. ( 1873a) On Some New Species of F o s s i l s from the P r i m o r d i a l or Potsdam Group of Rensselaer County, New York (Lower Potsdam); Am. Jour. S c i . 3 r d . s e r . , v o l . 5 , PP. 2 1 1 - 2 1 3 . 72 Ford, S.W. (1873b) Remarks on the D i s t r i b u t i o n of the F o s s i l s i n the Lower Potsdam Rocks at Troy, New York, w i t h D e s c r i p t i o n s of a few New Species; Am. Jour. S c i . , 3 r d . s e r . , v o l . 6, p. 135. (1878) D e s c r i p t i o n of Two New Species of P r i m o r d i a l F o s s i l s ; Am. Jour. S c i . , 3rd. s e r . v o l . 5 pp. 124. G i r l i n g , V. (1954) Ecology of the Arehaeocyatha; Bachelor of A r t s T h e s i s , U n i v e r s i t y of B r i t i s h Columbia. Hinde, G.J. (1889) On Archaeocyathus and Other Genera from the Cambrian S t r a t a of North America, Spain, S a r d i n i a , and S c o t l a n d ; Geol. Soc. London, Quart. Jour., v o l . 45, pp. 125-148. Lord, G.S. (1944) G e o l o g i c a l Reconnaissance Along the Alaska Highway Between Watson Lake and T e s l i n R i v e r , Yukon and B r i t i s h Columbia; Geol. Survey Can., Paper 44-25, pp. 1-20. Matthew, G.F. (1885) I l l u s t r a t i o n s of the Fauna of the S t . John Group; Roy. Soc. Can. Trans., sec. 4, pp. 29-30. (1887) I l l u s t r a t i o n s of the Fauna of the S t . John Group; Roy. Soc. Can. Trans., sec. 4, pp. 160-165. (1890) I l l u s t r a t i o n s of the Fauna of the S t . John Group; Roy. Soc. Can. Trans., sec. 4, p. 123. Meek, F.B. (1868a) P r e l i m i n a r y Notice of a Remarkable New Genus of C o r a l s , Probably T y p i c a l of a New Family; Am. Jour. S c i . , 2nd. s e r . , v o l . 45, pp. 62-64. (1886b) Note on Ethmophyllum and Archaeocyathus; Am. Jour. S c i . , 2nd. s e r . , v o l . 46, p. 144. O k u l i t c h , V.J. (1935) Cyathospongia A New Class of P o r i f e r a to Include the Archaeocyathlnae; Roy. Soc. Can. Trans., 3 r d , s e r . , sec. 4, v o l . 29, pp. 75-106. (1940) R e v i s i o n of Type Pleospongia from Eas t e r n Canada; Roy; Soc. Can. Trans., 3 r d . s e r . sec. 4, v o l . 34, pp. 75-87. 73 O k u l i t c h , V.J.(1943) North America Pleospongia; Geol. Soc. Am., Paper 48, pp. 1-112. (1946) Exothecal Lamellae of the Pleospongia; Roy. Soc. Can. Trans., 3rd. s e r . , sec. 4, v o l . 40, pp. 73-86. (1948) Lower Cambrian Pleospongia from the P u r c e l l Range of B r i t i s h Columbia, Canada; Jour. P a l . v o l . 22, no. 3 , pp. 340-349. (1952) Pleospongia, i n Cambrian S t r a t i  graphy and Paleontology near Caborca, Mexico; Smithsonian Misc., C o l l . , v o l . 119, no. 1, PP. 25-37. (1954) Arehaeocyatha from the Lower Cambrian of Inyo County, C a l i f o r n i a ; Jour. P a l . , v o l . 28, no. 3 , PP. 2 9 3 - 2 9 6 . (1955a) Arehaeocyatha; T r e a t i s e on I n v e r t  ebrate Paleontology, P a r t E, edited by Moore, R.C. pp. E1-E20. (1955b) Arehaeocyatha from the McDame Area of Northern B r i t i s h Columbia; Roy. Soc. Can. Trans., 3rd. s e r . , see. 4, v o l . 44, pp. 47-64. O k u l i t c h , V.J. and de Laubenfels, M.W. (1953) The Systematic P o s i t i o n of Arehaeocyatha (Pleospongia); Jour. P a l . , v o l . 2 7 , no. 3, pp. 481-485. O k u l i t c h , V.J., and Roots, E.F. (1947) Lower Cambrian F o s s i l s from the Iaken Lake Area, B r i t i s h Columbia; Roy. Soc. Can. Trans., 3rd, s e r . , sec. 4, v o l . 41, pp. 37-46. Poole, W.H. (1955) P r e l i m i n a r y Map of Wolf Lake Area, Yukon T e r r i t o r y ; Geol. Survey Can., P r e l i m i n a r y Map 55-21. Raymond, P.E. (1931) Systematic P o s i t i o n of the Archaeo- cyathinae; Mus. Comp. Z o o l . , Harvard Univ., v o l . 56, p. 1 7 2 . Shimer, H.W. and Shrock, R.R. (1943) Index F o s s i l s of North America, pp. 5 6 - 5 7 . 74 Simon, W. (1939) Archaeoeyathacea. I . K r i t i s c h e Sichtung der S u p e r f a m i l i e . I I . Die Fauna im Kambrium der S i e r r a Morena (Spanien); Abhandlungen der Sencken- bergischen Naturforschenden G e s e l l s c h a f t \ Adbhandlung 4 4 8 , pp. 1 - 8 7 . T a y l o r , T.G. (1907) P r e l i m i n a r y Note on Archaeocyathinae from the Cambrian C o r a l Reefs of South A u s t r a l i a ; A u s t r . Assoc. Adv. S c i . , pp. 1 -15 . (1910) The Archaeocyathinae from the Cambrian of South A u s t r a l i a ; Roy. Soc. S. A u s t r . , Mem. v o l . 2 , p t . 2 , pp. 5 5 - 1 8 8 . V o l o g d i n , A.G. (193D Archaeocyathae of S i b e r i a , P t . 1. Faunas of the Limestone of Ulus Bei-Buluk and Kameshki V i l l a g e , Minusinsk Region, and of N i j n a y a Ters R i v e r , Kuznetsk D i s t r i c t ; United Geol. Prosp. Survey, U.S.S.R., pp. 1 -119. (1932) Archaeocyathinae of S i b e r i a , P t . 2 . F o s s i l s of the Cambrian Limestone of A l t a i Moun t a i n s ; United Geol. Prosp. Survey, U.S.S.R., pp. 1 - 1 0 6 . (1937) Archaeocyatha and the Results of The i r Study i n the U.S.S.R.; Problems i n P a l . , v o l s . 2-3, Lab. of P a l . , Moscow Univ. pp 453-500. (1939) Middle Cambrian Archaeocyatha and Algae from the South U r a l s ; Problems i n P a l . , v o l . 5, Lab. of P a l . , Moscow Univ., pp. 209-276. (1940) Subtype Archaeocyatha: A t l a s of Leading Forms of the F o s s i l Faunas of the U.S.S.R. v o l . 1 , Cambrian; S t a t e E d i t o r i a l O f f i c e f o r Geol. L i t e r a t u r e , Moscow. Walcott, C D . (1886) Cambrian Faunas of North America; U.S. Geol. Survey, B u l l . 3 0 , pp. 72-89. Zhuravleva, I.T. (1955) Archaeocyatha of the Cambrian of the East Slope of Kuzhetzk Ala-TauJ Academy of S c i . of U.S.S.R. C o n t r i b u t i o n s of the Paleonto- l o g i c a l I n s t i t u t e , v o l . 5 6 , pp. 7 - 5 6 . 75 EXPLANATION OF PLATES PLATE I Fi£S. 1. A.lacicyathus p u r c e l l e n s i s O k u l i t c h X l£, No. 3 6 - Y - 6 , G.S.C. Transverse t h i n s e c t i o n showing w a l l s and p a r i e t i e s . 2. A.lacicyathus yukonensis n. sp. X4, Holotype, No. 35-Y-131 , G.S.C. Transverse t h i n s e c t i o n show i n g inner and outer w a l l s and simple p a r i e t i e s . 3 . Ethmocoscinus sp. X l£. No. AP-7, U.B.C. Trans verse t h i n s e c t i o n showing wide i n t e r v a l l u m and t h i c k , v e s i c u l a r inner w a l l . 4» Coscinocyathus dentocanis O k u l i t c h X l*jr. No. 40-Y-4, G.S.C. Transverse t h i n s e c t i o n . 5 . Coscinocyathus dentocanis O k u l i t c h X 1^. No. 40-Y-4, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n show ing tabulae. 6 . Coscinocyathus dentocanis O k u l i t c h X l£. No. 40-Y - 6 , G.S.C. Transverse t h i n s e c t i o n showing e l l i p t i c a l shape and simple r a d i a l p a r i e t i e s c r o s s i n g the i n t e r v a l l u m . 7. Gosclnocyathus multlporus n. sp. X 1-jjr. Holotype, No. 35-Y-13II, G.S.C. Transverse t h i n s e c t i o n showing porous p a r i e t i e s and tabulae. 8 . Coscinocyathus multlporus n. sp. X l£. Holotype, No. 3 5-Y-13H, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing inner w a l l , p a r i e t i e s , and tabulae. 9 . Coscinocyathus multlporus n. sp. X l£. Holotype, No. 35-Y-1311 , G.S.C. Transverse t h i n s e c t i o n , taken near the base of the specimen, showing narrow c e n t r a l c a v i t y and thickened p a r i e t i e s . 76 10. Coscinocyathus c a s s i a r l e n s i s n. sp. X2. Holotype, No. 35-Y-7, G.S.C. Transverse t h i n s e c t i o n showing porous r a d i a l p a r i e t i e s . 11. Coscinocyathus c a s s i a r l e n s i s n. sp. X 2. Paratype, 3 5-Y - 8 , G.S.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s . 12. Coscinocyathus c a s s i a r i e n s i s n. sp. X 2. Holotype, Nd. 35-Y-7, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing tabulae and p a r i e t i e s . 13* Coscinocyathus c a s s i a r i e n s i s n. sp. X 2. Paratype, No. 3 5-Y - 9 , G.S.C. Transverse t h i n s e c t i o n of la r g e fragmental specimen. 77 PLATE I I Figs. 1. Coscinocyathus i n e q u i v a l i u s n. sp. X 1.75. Holotype, No. AP-14, U.B.C. L o n g i t u d i n a l s e c t i o n showing tabulae, p a r i e t i e s , and c e n t r a l c a v i t y . 2. Coscinocyathus i n e q u i v a l l u s n. sp. X : 3 . Holotype, No. AP-14, U.B.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s , t a b u l a e , and inner w a l l . 3. Coscinocyathus i n e q u i v a l l u s n. sp. X 3. Paratype, No. AP-13, U.B.C. Transverse t h i n s e c t i o n . 4. Coseinocyathus i n e q u i v a l l u s n. sp. X 1^ -. Paratype, No. AP-19, U.B.C. L o n g i t u d i n a l s e c t i o n showing p a r i e t i e s . 5. Coscinocyathus i n e q u i v a l l u s n. sp. X 3. Paratype, No. AP-15, U.B.C. Transverse t h i n s e c t i o n of l a r g e specimen, and oblique s e c t i o n of s m a l l e r one showing tabulae. 6. Coscinocyathus i n e q u i v a l l u s n. sp. X 2. Paratype, No. AP-16, U.B.C. Oblique t h i n s e c t i o n showing weak annu l a t i o n of outer w a l l . 7. Coscinocyathus s e r r a t u s n. sp. X 2. Holotype, No. AP-17, U.B.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s and complex inner w a l l . 8. Coscinocyathus veronicus n. sp. X l£. Holotype, No. 40-Y2, G.S.C. Transverse t h i n s e c t i o n showing narrow i n t e r v a l l u m and r a d i a l p a r i e t i e s . 9 . Coscinocyathus s e r r a t u s n. sp. X 1 .8 . Holotype, No. AP-17, U.B.C. L o n g i t u d i n a l s e c t i o n showing tabulae and inner w a l l . 78 10» Coscinocyathus tubicornus n. sp. X 2 . Holo type, No. 3 6 - Y - l l , G.S.C. Transverse t h i n section showing wide intervallum and porous p a r i e t i e s . 1 1 . Coscinocyathus tubicornus n. sp. X 0 . 7 5 Holotype, No. 3 6 - Y - l l , G.S.C. Naturally weathered out specimen showing general form and tabulae. 1 2 . Coscinocyathus sp. X l*jr. No. 36-Y -10 , G.S.C. Transverse th i n section showing d e l i c a t e , r a d i a l p a r i e t i e s , and tabulae. Width of Intervallum i s about half the diameter of the central cavity. 79 PLATE I I I F i g s . 1. Carinacyathus perforatus n. sp. X I . Holotype No. 35-Y-12, G.S.C. N a t u r a l l y weathered out specimen. 2. Carinacyathus perfo r a t u s n. sp. X l£. Holotype No. 35-y-12, G.S.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s and porous tabulae c r o s s i n g the i n t e r v a l l u m . 3« Carinacyathus perforatus n. sp. X 1-jjr. Paratype, No. 35-y-10, G.S.C. Transverse t h i n s e c t i o n showing p a r i e t i e s and tabulae c r o s s i n g the i n t e r v a l l u m . 4. Carinacyathus perforatus n. sp. X l£. Paratype, No. 35-y-10, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing tabulae, p a r i e t i e s , and inner w a l l . 5. Carinacyathus perforatus n. sp. X 3. Holotype, No. 35-Y-12, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing complex inner w a l l , and perforated p a r i e t i e s and tabulae. 6. Archaeocyathus c f . a t l a n t i c u s B i l l i n g s X 1%, No7 "35-Y-14, G.S.C. Transverse t h i n s e c t i o n , taken from the upper p o r t i o n of the specimen, shovring i n t e r v a l l u m . 7. Archaeocyathus c f . a t l a n t i c u s B i l l i n g s , X l£. 35-y-14, G.S.C. Transverse t h i n s e c t i o n taken from near the base of the specimen. I n t e r  vallum of f l a t t e n e d specimen i s f i l l e d w i t h i r r e g u l a r wavy taeniae. 8. Archaeocyathus (?) sp. X l£. No. 41-Y-3, G.S.C. Transverse t h i n s e c t i o n showing i n t e r v a l l u m crossed, i n p a r t , by i r r e g u l a r t a e n i a e , and i n p a r t , by wavy p a r i e t i e s . Much of the i n t e r v a l l u m region i s replaced by c a l c i t e . i FLATE III 80 PLATE IV Figs. 1. Pycnoidocyathus amourensis ( O k u l i t c h ) X 2. No. 36-Y-9, G.S.C. Cross s e c t i o n showing wide i n t e r v a l l u m . Inner w a l l i s replaced by c a l c i t e . 2. Pycnoidocyathus columbianus ( O k u l i t c h ) X 1. No. AP - 2 2 , U.B.C. Cross s e c t i o n showing wavy p a r i e t i e s w i t h s y n a p t i c u l a e . 3. Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) X 0.6. No. 36-Y-12. G.S.C. N a t u r a l l y weathered out conical-shaped specimen. 4. Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) X l£. No. 36-Y-3, G.S.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s w i t h s y n a p t i c u l a e . 5« Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) X l£. No. 36-Y-2, G.S.C. Transverse t h i n s e c t i o n , taken from near the base, showing narrower c e n t r a l c a v i t y . 6. Pycnoidocyathus c f . o c c i d e n t a l i s ( O k u l i t c h ) X 1^ -. No. 36-Y-l, G.S.C. Transverse t h i n s e c t i o n showing p a r i e t i e s and pores of inner w a l l . 7» Pycnoidocyathus c f . d i s s e p i m e n t a l i s ( O k u l i t c h ) X 1 . 2 5 . No. AP - 2 5 , U.B.C. Cross s e c t i o n showing p a r i e t i e s and dissepiments. 8. Pycnoidocyathus s o l i d u s n. sp. X 2. Holotype, No. 40-Y-7, G.S.C. Transverse t h i n s e c t i o n , taken from near the base of the specimen, showing nature of c e n t r a l c a v i t y . 9. Pycnoidocyathus s o l i d u s h. sp. X 2. Holotype. No. 40-Y-7, G.S.C. Transverse t h i n s e c t i o n showing narrow c e n t r a l c a v i t y , and wide i n t e r v a l l u m crossed by wavy p a r i e t i e s w i t h s y n a p t i c u l a e . - LATE TV 81 PLATE V F i g s . 1. Loculicyathus e l l i p t i c u s n. sp. X 1^. Holotype, No. 3 5-Y-l, "G.S.C. Transverse s e c t i o n showing p a r i e t i e s and dissepiments i n the i n t e r v a l l u m . 2. Loculicyathus e l l i p t i c u s n. sp. X 2. Holotype, No. 3 5-Y-l, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing v e s i c u l a r t i s s u e . 3. Loculicyathus e l l i p t i c u s n. sp. X l£. Paratype, No. 35-Y-2, G.S.C. Transverse t h i n s e c t i o n showing i n t e r v a l l u m p a r t l y f i l l e d w i t h d i s s e p  iments and p a r t l y c l e a r . 4. Loculicyathus e l l i p t i c u s n. sp. X lJr. Paratype, No. 35/y-2, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing i n t e r v a l l u m r e g i o n . 5. Loculicyathus e l l i p t i c u s n. sp. X 2. Paratype, No. 35-Y-3, G.S.C. Transverse t h i n s e c t i o n showing r a d i a l p a r i e t i e s and dissepiments. 6. Loculicyathus e l l i p t i c u s n. sp. X 2. Paratype, No. 35.-Y-3, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing porous p a r i e t i e s . 7. Metacoscinus poolensis n. sp. X Ijjs-. Holotype, No. 40-Y-5, G.S.C. Transverse t h i n s e c t i o n showing p a r i e t i e s and dissepiments i n the i n t e r v a l l u m . 8. Metacoscinus poolensis n. sp. X 1^ -. Paratype, No. 40-Y-3, G.S.C. Transverse t h i n s e c t i o n showing p a r i e t i e s , dissepiments, and inner w a l l . 9. Metacoaclnus poolensis n. sp. X 3. Paratype, No. 40-Y-3, G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing tabulae and dissepiments. 10. Metacoscinus p o o l e n s i s , n. sp. X 1. Paratype, No. 4 0 - Y - l , G.S.C. Transverse t h i n s e c t i o n showing t h i n p a r i e t i e s and porous tabu l a e . PLATE V 82 11. Metacoscinus poolensis n. sp. X l£. Paratype, No. 4 0 - Y - l , G.S.C. L o n g i t u d i n a l t h i n s e c t i o n showing tabulae. 12. Metacoscinus sp. X 2. No. AP-6, U.B.C. Transverse t h i n s e c t i o n . 13. Claruscyathus ketzaensis n. sp. X 3, Holotype, No. AP-2, U.B.C. Transverse t h i n s e c t i o n showing i r r e g u l a r t a e n i a e . 14. Claruscyathus ketzaensis n. sp. X 2. Paratype No. AP-1, U.B.C. Transverse t h i n s e c t i o n showing t h i c k inner w a l l and i r r e g u l a r mass i n the i n t e r v a l l u m . Claruscyathus ketzaensis n. sp. X 3. Paratype, No. AP-3, U.B.C. Transverse t h i n s e c t i o n showing Ethmophyllum-like inner w a l l . 16. Claruscyathus ketzaensis n. sp. X 3. Paratype, No. AP-1, U.B.C. L o n g i t u d i n a l t h i n s e c t i o n showing s t e e p l y d i p p i n g tabulae. 

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