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A Lower Cambrian trilobite fauna from near Cranbrook, B.C. Best, Raymond Victor 1952

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fii  A LOWER CAMBRIAN TRILOBITE FAUNA " F R O M  NEAR"  CRANBROOK,  B.C.  by RAYMOND VICTOR BEST  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 to the standard r e q u i r e d of candidates f o r the degree of MASTER OF APPLIED SCIENCE.  Members of the  Department of  GEOLOGY AND GEOGRAPHY THE UNIVERSITY OF BRITISH COLUMBIA April,  1952  >  /f 7  ABSTRACT  T r i l o b i t e s t y p i c a l o f the w e l l known O l e n e l l u s zone o f the Lower Cambrian c o n s t i t u t e a l a r g e c o l l e c t i o n from the Eager Formation, near Cranbrook, B.C. and  T h e i r c l a s s i f i c a t i o n i s discussed,  two new s n e c i e s d e s c r i b e d : : O l e n e l l u s  n.sp.  eagerenals  and O l e n e l l u s s c h o f i e l d l r&spjV Since the use o f c e r t a i n s t r u c t u r e s i n  c l a s s i f y i n g o l e n e l l i d s has been d i s p u t e d  i n the p a s t ,  these and other l e s s c o n t r o v e r s i a l f e a t u r e s a r e c r i t i c a l l y examined, i n s o f a r as they apply t o the genera and s p e c i e s  present.  From t h i s study the w r i t e r assembles c r i t e r i a which might be used by l a t e r workers t o r e d e f i n e the g e n e r i c and s p e c i f i c p o s i t i o n s o f s e l e c t e d s p e c i e s o f O l e n e l l u s and Faedeumias^  TABLE OP CONTENTS ABSTRACT  i  INTRODUCTION Acknowledgements Chapter I_  •— •  11 iv  ---  CRANBROOK AREA  H i s t o r i c a l Summary — Stratigraphy — • — L i t h o l o g y of the O l e n e l l u s Zone  r  1 3 4  Introduction — — — • Terminology — — • — — —. .— Terminal Segments — •— F a c i a l Sutures •— .-C e p h a l i c Spines ; — — — . — F r o n t a l Lobe and Brim -—— • -— Hypostoma and E p i s t o m a l P l a t e — Thorax : -——.— • P o s t - O c u l a r Nodes -•Ornamentation • —— Growth Stages • —— • Preservation — • ••— C e p h a l i c and T h o r a c i c R a t i o s — • Systematic P o s i t i o n of O l e n e l l i d s = Generic and S p e c i f i c D i s t i n c t i o n s - - — Recommendations f o r F u r t h e r Study •  6 7 7 9 12 13 15 .17 19 20 21 23 26 27 28 30  Chapter I I  •  TAXONOMIG.. CONSIDERATIONS -  ;  :  Chapter I I I  DESCRIPTION OF GENERA AND SPECIES  Q l e n e i l u s —•  — < — •  31  O l e n e l l u s .of., g i l b e r t ! O l e n e l l u s ea^erenaIs. n . sp> - O l e n e l l u s . . . s o h o f i e l d l . n . s p . .—  Paedeumias • Paedeumias nevadensis Wanner i a ? Wanner l a walcottana T  •  •-• •—  «  •  -—-•—-—•  .  :  Bonnla Bonnla e-f-.  —  42  44 45 47  -r—  ? Qolumbensls  35 37 40  .-  49 50  -  52  EXPLANATION OF PLATES  56  BIBLIOGRAPHY  ILLUSTRATIONS —•  Olenellus g l l b e r t l  Table I  C e p h a l i c and T h o r a c i c R a t i o s  27  Table I I  P o s s i b l e Generic D i s t i n c t i o n s  29  Plate I  O l e n e l l u s eagerensis ri» sp« and O l e n e l l u s s c h o f i e l d i . n. sp> - F a c i n g Page —  56  Plate II  —  •  Frontispiece  Paedeumias nevadensls. O l e n e l l u s o f . g i l b e r t i . Wanneria walcottana and Bonnla c f . columbensis". F a c i n g Page 57  li.  A LOWER CAMBRIAN TRILOBITE FAUNA "FROM NEAR. CRANBROOK,'B.C.*.  INTRODUCTION  The f o l l o w i n g study c o l l e c t i o n of t r i l o b i t e s , Garrett,  i s based upon a  made l a r g e l y by Mr. C.  l a t e of Granbrook, B . C . , and bought by  the U n i v e r s i t y of B r i t i s h Columbia. was taken from two l o c a l i t i e s  The c o l l e c t i o n  of d i f f e r i n g  logy w i t h i n the Eager F o r m a t i o n .  It  consists  almost e n t i r e l y of t r i l o b i t e s t y p i c a l known O l e n e l l u s zone, which d e f i n e  litho-  of the  the age of  well the  rocks i n which they were found as Lower Cambrian. I t may be t h a t c o n c l u s i o n s based on observations  of fauna from a s i n g l e l o c a l i t y  be r e s t r i c t e d to t h a t p a r t i c u l a r a r e a .  should  A student  f a c e d w i t h . o n l y one phase of a l a r g e r problem may be-tempted t o e x t r a p o l a t e generalizations  can be quoted from the  analogous t o those an e l e p h a n t .  unreasonably.  Many literature  of the t h r e e b l i n d men d e s c r i b i n g  But i n the wider f i e l d o f  paleontologi-  c a l r e s e a r c h a c l u e t o one o f the l a r g e r problems may l i e at some s i n g l e l o c a l i t y , t i o n of a t e n t a t i v e h y p o t h e s i s an accepted p r i n c i p l e .  providing confirma-  or the r e f u t a t i o n o f  ill The w r i t e r r e g r e t s the l a c k of time to continue the study of t h i s e x c e l l e n t It  collection.  i s almost c e r t a i n t h a t o n l y a few of  legitimate  s p e c i e s have been r e c o g n i z e d .  the A great  d e a l more c o u l d be l e a r n e d of the o n t o g e n i e s , and p o s s i b l y of s p e c i f i c  and g e n e r i c r e l a t i o n s h i p s , of  the o l e n e l l i d s , from the scores of Immature specimens. No doubt t o o , a d d i t i o n a l m a t e r i a l c o l l e c t e d by palaeontologists  conversant w i t h the o u t s t a n d i n g  problems would p r o v i d e much v a l u a b l e i n f o r m a t i o n from the s t r a t i g r a p h l c and e c o l o g i c a l p o i n t s of v i e w . In s p i t e of the l i m i t a t i o n s of time and experience,  i t i s hoped t h a t the o b s e r v a t i o n s made  here w i l l be of some v a l u e i n f u r t h e r s t u d i e s of the o l e n e l l i d s as a whole  8  it:  ACKNOWLEDGEMENTS  The w r i t e r g r a t e f u l l y the guidance and c o n s t r u c t i v e  acknowledges  c r i t i c i s m of  D r . V . J e O k u l i t c h i n the p r e p a r a t i o n of thesis, ing  and I n v a l u a b l e a s s i s t a n c e  this  i n photograph-  specimens. To D r . M.Y« W i l l i a m s s p e c i a l  thanks  are due f o r p r o v i d i n g much general, i n f o r m a t i o n , but p a r t i c u l a r l y f o r the l o a n of h i s p e r s o n a l , c o l l e c t i o n of o l e n e l l i d t r i l o b i t e s . Mr. W. Armstrong and Mr. J . F i s h e r of the Department of M i n i n g and M e t a l l u r g y k i n d l y encouraged and a s s i s t e d at  micro-photography.  i n experimental  attempts  1. CHAPTER I CRANBROOK AREA  H i s t o r i c a l Summary  The f i r s t extensive  geological  work i n the  Granbrook Area-was c a r r i e d out by s c h o f i e l d  (1915,  P r i o r to h i s 1915 memoir b r i e f r e c o n n a i s s a n c e s made by Dawson (1895) and McEvoy (1899).  1922).  had been  The most  r e c e n t r e v i s i o n of s t r a t i g r a p h y near Granbrook was comp l e t e d by R i c e Is  (1937, 1941)  i n c l u d e d i n the p r e s e n t The presence  a copy of whose 1937 map paper.  of the O l e n e l l u s zone was  r e p o r t e d between Granbrook and P o r t S t e e l e by (1922).  The f o s s i l s  Waleott,  who I d e n t i f i e d  Schofield  he c o l l e c t e d were sent to the f o l l o w i n g  Gallavla of.  nevadensis  first  CD.  trilobites: Waleott  Wannerla n . sp ? Mesonaois g i l b e r t i  Meek  Wannerla o f .  waloottanus  Olenellus cf.  fremontl  Prototypus  seneotus  (Wanner) Waleott  Billings  Waleott i s quoted c o n c e r n i n g t h i s saying:  " T h i s fauna belongs  Lower Cambrian and i t  c o l l e c t i o n as  to the upper p a r t of  is essentially  the same as  the that  found above the t u n n e l at Mt. Stephen, B . C . , and i s  also  1. Dates i n parentheses r e f e r to the B i b l i o g r a p h y i n the back of the r e p o r t .  2. found more o r l e s s a l l a l o n g t h e c o r d i l l e r a n  system  down i n t o southern Nevada." ( I b i d , p 12) The s p e c i e s found by R i c e (1937) a p p a r e n t l y did  not d i f f e r t o any g r e a t e x t e n t , s i n c e no f u r t h e r  f a u n a l i n f o r m a t i o n i s embodied i n h i s r e p o r t . A l t h o u g h p r o f e s s i o n a l g e o l o g i s t s were mainly i n t e r e s t e d i n the Cranbrook.Area.from  an economic  p o i n t of view, a t l e a s t two amateurs became v e r y keen f o s s i l hunters.  C o l . P u l l e n and C. G a r r e t t made exten-  s i v e c o l l e c t i o n s of t r i l o b i t e s and other f o s s i l s  from  two l o c a l i t i e s , one on the main Cranbrook-Fort S t e e l e road, the second j u s t e a s t o f S t . Eugene M i s s i o n . I n this, second l o c a l i t y they p u t i n a s m a l l a d i t i n grey shale and were rewarded.by o b t a i n i n g a v e r y f i n e c o l l e c t i o n , including•numerous growth-stages  examples of t h e young  o f O l e n e l l u s , Paedeumias and Wanneria.  Unfortunately, c e r t a i n l o c a l  inhabitants,  s u s p e c t i n g t h a t such incomprehensible a c t i o n s were conn e c t e d with something more remunerative than a " t r i l o b i t e mine", s t a k e d out c l a i m s .  C o l l e c t i n g had t o be" d i s -  c o n t i n u e d and the a d i t f i l l e d i n . Dr. M.Y. W i l l i a m s of the U n i v e r s i t y of B r i t i s h Columbia made a f a i r l y e x t e n s i v e c o l l e c t i o n from b o t h  l o c a l i t i e s i n 1954, The G a r r e t t c o l l e c t i o n , o b t a i n e d l a t e r by the U n i v e r s i t y , t o g e t h e r w i t h t h a t o f Dr. W i l l i a m s , t o t a l s some f o u r t e e n hundred specimens, and f u r n i s h e s the m a t e r i a l f o r t h i s s t u d y . STRATIGRAPHY The presence o f Bonnla and O l e n e l l u s i n the Eager Formation p l a c e s the age o f these r o c k s i n the upper p a r t o f the Lower Cambrian The Eager a r g i l l i t e s ,  ( R a s e t t i , 1951)•  some thousands of f e e t t h i c k , are  u n d e r l a i n by the Granbrook Formation, which I s 600 f e e t thick. Rice  The c o n t a c t between these two i s b e l i e v e d by  (1941) t o be g r a d a t i o n a l .  The Cranbrook Formation  c o n s i s t s l a r g e l y o f q u a r t z i t e , pebble conglomerate, and some magnesite; although f o s s i l s a r e absent, i t s age i s a l s o a s s i g n e d t o the Lower Cambrian.  The Cranbrook r e s t s  uneonformably on P r o t e r o z o i c r o c k s o f Upper P u r c e l l Age. The age r e l a t i o n s h i p s of the Lower Cambrian O l e n e l l u s zone have r e c e n t l y been s t u d i e d by R a s e t t i (1951)•  T e n t a t i v e l y the Eager Formation may be c o r -  r e l a t e d w i t h Peyto limestone, t h a t i s , the top o f the Lower Cambrian S t . P i r a n sandstone a t K i c k i n g Horse Pass.  I t i s a l s o c o r r e l a t e d w i t h the lower p a r t o f  the B u r t o n Formation a t E l k o  ( S c h o f i e l d , 1922).  4 LITHOLOGY OF THE OLENELLUS ZONE I t i s s t a t e d by Resser and Howell p. 207)  (1938,  that:  "The l i t h o l o g i c s i m i l a r i t y of Lower Cambrian s t r a t a i n a l l p a r t s of the world i s a s t o n i s h i n g , and t h i s s i m i l a r i t y i s p a r t i c u l a r l y .noticeable i n the s h a l e s b e a r i n g o l e n e l l i d t r i l o b i t e s . For ... , the most p a r t , these r o c k s are c l a y s h a l e s , i n .r many p l a c e s c a l c a r e o u s , but everywhere f i n e g r a i n e d ; the J o i n t s u r f a c e s are almost u n i v e r s a l l y s t a i n e d w i t h l i m o n i t e g e n e r a l l y i n d e n d r i t i c form. Moreover there was s u f f i c i e n t c a l c a r e o u s content i n the o r i g i n a l muds to prevent many t e s t s from b e i n g completely f l a t t e n e d . " The Eager Formation i s no e x c e p t i o n to t h i s A c c o r d i n g to R i c e (1937, p.  statement.  21)  "The b u l k of the f o r m a t i o n c o n s i s t s of dark grey, o f t e n r u s t y - w e a t h e r i n g a r g i l l i t e ... B l u e grey, o l i v e green, and. r e d d i s h p l a t y a r g l l l i t e s a l s o occur i n p l a c e s . They are a l l s o f t , e a s i l y deformed rocks and are everywhere f o l i a t e d . The f o r m a t i o n i s not g e n e r a l l y l i m y , but beds' of c a l c a r e o u s a r g i l l i t e may occur i n any p a r t o f i t ..." I t i s apparent from the f o r e g o i n g statements t h a t the O l e n e l l u s zone i s p e c u l i a r to a somewhat r e s t r i c t e d type of l i t h o l o g y .  But w i t h i n the zone  i n t h i s case the Eager Formation,  certain peculiarities  of f a u n a l d i s t r i b u t i o n a r e s u p e r f i c i a l l y  apparent.  The t r i l o b i t e s were c o l l e c t e d from two l i t i e s named here A and B.  itself,  At l o c a l i t y A#  Cranbrook-Fort S t e e l e r o a d (see map  °*i  t l i e  locamain  i n back cover) the  rocks are s o f t l i m o n l t i c a r g l l l i t e s ; a t B, j u s t  south  5. of  S t . Mary R i v e r and e a s t of S t . Eugene M i s s i o n ,  they c o n s i s t of harder, dark grey,  rusty-weathering,  d o l o m i t i c , sometimes sandy a r g i l l i t e s .  At  both  - l o c a l i t i e s the dominant forms are O l e n e l l u s e f . g i l b e r t l and Paedeumias nevadensls;  but a t B, not  only  Is the p r o p o r t i o n of 0. e a g e r e n s l s h i g h e r , but here were found the only spec imens r e f e r r e d to 0. and to Bonnia c f .  schofieldl  columbensls'.  Since the w r i t e r d i d not c a r r y out the l e c t i n g h i m s e l f , numbers of i m p e r f e c t or specimens may "weighting"  col-  incomplete  have been abandoned, w i t h consequent  of the p r o p o r t i o n s of s p e c i e s c o l l e c t e d .  Furthermore, the s t r a t i g r a p h i c r e l a t i o n s h i p of the outcrops  two  i s not known,, so t h a t i t i s p o s s i b l e t h a t  e n t i r e l y d i f f e r e n t ages w i t h i n the O l e n e l l u s zone are represented". Although  no p o s i t i v e c o n c l u s i o n may  be drawn  from these o b s e r v a t i o n s of f a u n a l d i s t r i b u t i o n ,  the  f a c t s do not, a t l e a s t , c o n t r a d i c t the s u g g e s t i o n made by R a s e t t i (1951, P 82)s "The O l e n e l l u s zone may r e p r e s e n t a s h a l y f a d e s of the Lower Cambrian d e p o s i t s r a t h e r than a d e f i n i t e time i n t e r v a l . In northwestern Vermont, f o r example, o l e n e l l i d s . s e e m t o p r e v a i l when the Lower Cambrian i s r e p r e s e n t e d by s i l i c i o u s . s h a l e s , while Bonnla and s m a l l p t y c h o p a r i d t r i l o b i t e s are dominant i n limestone or d o l o m i t i c formations, r e g a r d l e s s of age.' _ 1  CHAPTER I I TAXONOMIC CONSIDERATIONS  Introduction P r o b a b l y no group of t r i l o b i t e s has aroused more c o n t r o v e r s y and d i s c u s s i o n than the They are unique i n many ways. p e c u l i a r i t y was not r e c o g n i z e d ,  olenellids.  But f o r years  their  and the g r e a t e s t  efforts  were made to f i t  them i n t o e s t a b l i s h e d schemes of  classification,.  Much of the t r o u b l e stemmed from the  o l d e r conceptions of e v o l u t i o n .  A l a t e r form,  showing  s u p e r f i c i a l resemblance to another-, l i v i n g perhaps m i l l i o n s of years e a r l i e r , was c o n s i d e r e d t o be s a r i l y on the d i r e c t l i n e of d e s c e n t .  Homologizlng  of p a r t s was s t i l l a new i d e a i n the l a s t great  neces-  century,  s c i e n t i f i c v a l u e , b u t c a r r i e d to extremes-.  t r a c e s of these abuses have l i n g e r e d on to the  of Some  present  day. The c o n t r o v e r s y a r i s i n g i n the study o f o l e n e l l i d s was concerned mainly w i t h the and o r i g i n of two or three f e a t u r e s t e r m i n a l segments,  cephalic sutures,  extent, cephalic spines.  development  of the  carapace:  and to a l e s s e r  Since an attempt  i s made i n  t h i s paper t o augment e s t a b l i s h e d c r i t e r i a f o r d i s t i n g u i s h i n g the s h i e l d s of c e r t a i n t r i l o b i t e s , features  the  above  and some others of a l e s s c o n t r o v e r s i a l n a t u r e  are d i s c u s s e d i n s o f a r as they apply to the genera and  7. species  examined.  Furthermore, a l t h o u g h the  genus  Mesonacls has heen d e c l a r e d i n v a l i d (Resser and Howell 1938), i t  i s p o s s i b l e t h a t at some f u t u r e  time enough  d a t a w i l l have been compiled to permit the r e l n t r o d u c t i o n of t h i s c o n t r o v e r s i a l name. mind the w r i t e r i n d i c a t e s p o s s i b l e r e d e f i n i t i o n o f "Mesonacls"  With t h i s  in  c r i t e r i a for a  (B.B.)'.  TERMINOLOGY The terminology used throughout t h i s is essentially  t h a t of Howell e t a l *  paper  (1947) w i t h some  of the m o d i f i c a t i o n s suggested by Ross (1948) and adopted by R a s e t t i  (1951)•  Since i t i s suggested t h a t the a n t e r i o r of the cephalon o f o l e n e l l i d s i s not separable and f r e e  cheeks,  into  fixed  the "brim" Is r e s t r i c t e d i n t h i s  to mean that p a r t of the c e p h a l i c s u r f a c e l y i n g between the f r o n t a l lobe and the  at the  paper centre,  rim*  To a v o i d t e d i o u s r e p e t i t i o n , the a x i a l  spine  on the 15 t h o r a c i c segment i s o c c a s i o n a l l y r e f e r r e d t o as "the 1 5 t h s p i n e " , even when other s p i n e s are not present on segments  a n t e r i o r t o the  15th*  TERMINAL SEGMENTS The rudimentary p o s t e r i o r segments are only r a r e l y observed.  of  Under c o n d i t i o n s of  olenellids almost  8. p e r f e c t p r e s e r v a t i o n they may be concealed by the massive a x i a l spine on the 15th  segment,  - f o l d e d forward under the t h o r a x .  o r perhaps  I n most specimens,  s i n c e these segments were p r o b a b l y v e r y f r a g i l e , seem to have been l o s t  they  entirely.  For many years G.D. Walcott was an i n f l u e n t i a l proponent of the theory t h a t Olenellus  was a t e l s o n ,  modem k i n g c r a b .  the 15th  spine on  l i k e t h a t on L i m u l u s , the  The presence of t e r m i n a l segments  and s m a l l p y g i d i a i n a l l other o l e n e l l i d genera d e c i d e d him to s e t up Mesonaols r a t h e r t h a n O l e n e l l u s as the type-genus of the f a m i l y Mesonacldaev M. vermontana. was known to possess segments,  The  genotype,  t e n rudimentary  and a s m a l l pygidium, p o s t e r i o r to the  b e a r i n g 15th  thoracic  spine-  segment.  During the course of time, more and more specimens r e p r e s e n t i n g e s t a b l i s h e d s p e c i e s  of O l e n e l l u s  were found to possess rudimentary segments,  necessitating  t h e i r t r a n s f e r , by Walcott and h i s f o l l o w e r s ,  to  Mesonacis or Paedeumias, the n e a r e s t r e l a t e d genera known to possess  such  features.  Resser (1928) a f t e r  showing c o n c l u s i v e l y  t h a t O l e n e l l u s d i d Indeed possess rudimentary p o i n t e d out t h a t d i f f e r e n c e s  i n these c o u l d be  segments, detected  9. a t the g e n e r i c l e v e l ; those, o f Mesonacls had d e f i n i t e , grooved p l e u r a e , those of O l e n e l l u s had ungrooved p l e u r a e , out those of Paedeumias l a c k e d p l e u r a e altogether. In 1 9 3 8 , Resser and Howell,  i n r e v i s i n g the  genus O l e n e l l u s e s t a b l i s h e d the f a c t t h a t i t s p o s t e r i o r segments d i d not n e c e s s a r i l y possess p l e u r a e .  Generic  r e d e s c r i p t i o n i n c l u d e d c e r t a i n o t h e r c h a r a c t e r i s t i c s , so as t o Include forms f o r m e r l y named Mesonacls.  Thus,  the names Mesonacls and Mesonacidae were dropped. Observations With the e x c e p t i o n o f Wannerla w a l c o t t a n a . -the specimens i n the c o l l e c t i o n , a l t h o u g h w e l l p r e s e r v e d , g e n e r a l l y e x h i b i t n e i t h e r the p o s t e r i o r segments nor the. pygidlum.  rudimentary  I n n e a r l y every complete  thorax of O l e n e l l u s and Paedeumias the 1 5 t h s p i n e i s extremely heavy, i t s base extending f u l l y a c r o s s the a x i a l l o b e , and t a p e r i n g f a i r l y s l o w l y , so t h a t i t e f f e c t i v e l y c o n c e a l s whatever l i e s beneath.  One s p e c i -  men o f O l e n e l l u s c f . a l l b e r t i has no l e s s than t h r e e v e r y p o o r l y p r e s e r v e d segments p o s t e r i o r t o the s p i n e - b e a r i n g 15th,  b u t no pygidium has been  observed.  FACIAL SUTURES The c l a s s i f i c a t i o n o f t r l l o b i t e s i s l a r g e l y based upon the development and p o s i t i o n of the f a c i a l  10'. suture,  o r l i n e of J u n c t i o n of the f i x e d and f r e e  cheeks of the c e p h a l o n .  It  i s g e n e r a l l y assumed  t h i s was.the l i n e along which the t r i l o b i t e s p l i t during ecdysis, a l l Crustacea.  It  cephalon  the p e r i o d i c m o u l t i n g common t o  i s p o s s i b l e t h a t the s u t u r e s  t r i l o b i t e s are not i n v a r i a b l y homologous. to Stubblefield  that  of  According  (1936, p 410):  " I t cannot be d e n i e d t h a t the presence o f c e p h a l i c sutures f a c i l i t a t e d e c d y s i s , but i t i s a t l e a s t arguable t h a t the sutures e x i s t e d o n l y f o r t h i s purpose.?' The o l e n e l l i d s have l o n g been a source of difficulty possess I.e.  i n taxonomy,  s i n c e they do not appear  these u s e f u l s t r u c t u r e s  as a means of f a c i l i t a t i n g  i n functional ecdysisv  t i o n s , made of specimens s i n c e the f i r s t of O l e n e l l u s preted.  and S t u b b l e f i e l d  inter-  over  the  i s g i v e n by Raw (1937)  (1936).  Briefly,  the main o p i n i o n s c o n c e r n i n g  sutures and t h e i r s i g n i f i c a n c e r.  description  A complete h i s t o r y o f the d i s p u t e s i n olenellids  form,  Observa-  ( H a l l , 1859) have been v a r i o u s l y  f a c i a l sutures  to  facial  may be summarized:  Rudimentary - i n p r o c e s s of o r i g i n or synthesis. (Ibid).  2. V e s t i g i a l - or i n a c o n d i t i o n o f (Raw, 1937).  symphysis.  11. Observations In examining  n e a r l y 500 complete  cephala  o f O l e n e l l u s and Paedeumias.the w r i t e r has made a number o f o b s e r v a t i o n s : 1. The tendency f o r the cephalon t o break i n certain places i s indisputable. The l i n e s of a n t e r o - l a t e r a l f r a c t u r e , i n t e r p r e t e d by B e l l (1931) and o t h e r s as f a c i a l sutures,have c e r t a i n c h a r a c t e r i s t i c s . (a) They a r e seldom s y m m e t r i c a l l y  developed.  (b) Ho two cephala have been found w i t h the f r a c t u r e s i d e n t i c a l . (c) They a r e no more f r e q u e n t i n occurrence than the l o n g i t u d i n a l l i n e o f f r a c t u r e down the approximate c e n t r e o f the glabella. (d) Unbroken cephala show no l i n e , r a i s e d or depressed, s u g g e s t i v e o f an i n h e r i t e d l i n e of weakness i n t h i s d i r e c t i o n . I t i s suggested, t h e r e f o r e , t h a t these f r a c t u r e s a r e e n t i r e l y mechanical i n o r i g i n , (see P r e s e r v a t i o n ) 2. The p o s t e r o - l a t e r a l r a i s e d l i n e r u n n i n g from under the eye toward the genal angle i s as o f t e n as not a s y m m e t r i c a l l y developed. Freq u e n t l y , t h i s l i n e separates i n t o two or more branches i n d i s t i n g u i s h a b l e from t h e v e n a t i o n r e f e r r e d t o by Lockman (1947, p. 6 1 ) . F r a c t u r e p r a c t i c a l l y never occurs a l o n g o r p a r a l l e l t o this line. I t appears t h a t i f t h i s p o s t e r o - l a t e r a l l i n e has s t r u c t u r a l s i g n i f i c a n c e i t i s n o t p a r t of a v e s t i g i a l f a c i a l s u t u r e , nor, i n i t s p r e s e n t form, does i t appear t o be a rudimentary suture i n the process of o r i g i n . 3» The i n t r a - m a r g i n a l sutures d e s c r i b e d by Resser (1928) i n O l e n e l l u s f r e m o n t i are c l e a r l y e x h i b i t e d i n t h i s c o l l e c t i o n i n the wider-rimmed specimens of O l e n e l l u s and Paedeumias, b u t even more s t r i k i n g l y i n the young stages of Wannerla walcottana.  12.. CEPHALIC SPINES In t h e i r e a r l i e s t l a r v a l stages o l e n e l l i d s may develop three p a i r s of c e p h a l i c s p i n e s .  Gf t h e s e ,  the g e n a l spines are r e t a i n e d as a prominent f e a t u r e i n a d u l t s of a l l genera; the i n t e r g e n a l s p i n e s o f t e n l o s t d u r i n g development;  are  the a n t e r o - l a t e r a l  w i t h the one e x c e p t i o n of O l e n e l l o i d e s a r e .  if  spines,  present  at a l l , r e s t r i c t e d e n t i r e l y to the-youngest i n d i v i d u a l s . I t was suggested "by Walcott  (1910, p .  237)  and has "been s t r o n g l y maintained by Raw (1937* p»  579)  t h a t the c e p h a l i c spines i n o l e n e l l i d s are segmental origin.  As S t u b b l e f i e l d p o i n t s out (1936, p. 425)  seems t o be l i t t l e  j u s t i f i c a t i o n f o r t h i s view.  in  there  Since  the i n t e r g e n a l spines i n O l e n e l l u s and Paedeumias appear to stem from the p r e - o c e i p i t a l g l a b e l l a r lobe and n o t , as Raw s t a t e d ,  from the o c c i p i t a l , much of h i s i n t e r p r e -  t a t i o n i s rendered i n v a l i d . There seems to be l i t t l e  doubt t h a t  r e t e n t i o n of c e p h a l i c s p i n e s Is a p r i m i t i v e  the  characteristic.  But whatever t h e i r f u n c t i o n , i f any (Raymond 1928,  p.  168) they are t a x o n o m i c a l l y u s e f u l * Observations No a n t e r o - l a t e r a l spines such as d e s c r i b e d by Walcott have been i d e n t i f i e d i n any of the l a r v a l o l e n e l l i d s  13. I n the c o l l e c t i o n , down t o the s m a l l e s t 1.25  cephalon,  mm In w i d t h , of Paedeumias. Intergenal  spines are more s t r o n g l y  developed  than the genals i n cephala: l e s s t h a n 5 mm. wide of 0'. c f g i l b e r t ! and P . n e v a d e n s i s , but g r a d u a l l y reduce i n comparative s i z e d u r i n g growth.  The i n t e r g e n a l  s p i n e s In these s p e c i e s are u s u a l l y l o s t when the cephalon i s about 15 mm. i n w i d t h . I n almost a l l specimens p o s s e s s i n g  Intergenal  s p i n e s , a r i d g e connects the spine almost d i r e c t l y a c r o s s the c h e e k - t o - t h e  r e a r of the p o s t - o c u l a r node,,  o p p o s i t e the o c c i p i t a l f u r r o w . FRONTAL LOBE AND BRIM The a n t e r i o r g l a b e l l a r lobe of o l e n e l l i d s u s u a l l y d i s t i n c t l y developed. its  Its  is  d i s t a n c e from the r i m ,  s i z e r e l a t i v e b o t h to the succeeding l o b e s and t o  the whole cephalon, and i t s c o n v e x i t y , used as a i d s i n c l a s s i f i c a t i o n .  have a l l been  The r e l a t i v e  size  the a n t e r i o r lobe t o a l a r g e e x t e n t governs the and t a p e r of the g l a b e l l a ' .  of  shape  The s e p a r a t i o n o f r i m from  g l a b e l l a by a b r i m p o s s e s s i n g an a x i a l r i d g e i s  diag-  n o s t i c of Paedeumias; the r i d g e i s p o s s i b l y due t o " . . . c o m p r e s s i o n of the t e s t onto the hypostoma during f o s s i l i z a t i o n . "  (Resser and Howell 1938  stalk p.  225)  14. Convexity i s i t s e l f a r e l a t i v e q u a n t i t y , most e a s i l y e s t i m a t e d i n terms of the abruptness of the r i s e of the a n t e r i o r l o b e from i t s own  frontal  margin.  Observations One  of the most s t r i k i n g f e a t u r e s of the  cephalon of O l e n e l l i i s eap;erensis a t a l l growth stages examined i s the extremely abrupt r i s e of the f r o n t a l l o b e from the narrow r i m . The f r o n t a l lobe of 0. c f . g i l b e r t i i s p r e ceded by a brim and r i m of approximately equal width. Between 0. c f . g i l b e r t 1 and P.  nevadensis  many t r a n s i t i o n a l forms have been observed, w i t h the width of the b r i m v a r y i n g from one to t h r e e times t h a t of the r i m .  The r i m i t s e l f v a r i e s i n width between  specimens otherwise i d e n t i c a l ; specimen M.YJ. i s t y p i c a l of 0. c f . g i l b e r t ! except f o r i t s broad rim (Pi.IE P i g . 8 ) • The growth stages o f 0. c f . g i l b e r t ! and P. nevadensis l e s s than 8-10  mm.  i n width are i n d i s t i n -  g u i s h a b l e ; the b r i m i s wide i n a l l cephala examined, and i n the b e t t e r p r e s e r v e d specimens possesses the t y p i c a l Paedeumias r i d g e . these two in this  Consequently,  a l l minute forms of  s p e c i e s are t o g e t h e r r e f e r r e d to "Paedeumias"  paper.  15  :  HYPOSTOMA AND EPISTOMAL PLATE The hypostoma, I f w e l l p r e s e r v e d , may be a valuable  aid i n I d e n t i f i c a t i o n of olenellids:.  most t r i l o b i t e s ,  i t i s a l i p - l i k e structure  As i n  fitting  convex down beneath the a n t e r i o r - g l a b e l l a r lobe;. hypostomae of Wannerla and Paedeumias from the localities  are equipped w i t h d e n t i c u l a t e  margins; i t  is believed  (Waleott,  The  type  posterior  1910, p . 328) t h a t  O l e n e l l u s g i l b e r t l possessed the same feature * 1  I n O l e n e l l u s and Paedeumias the hypostoma i s a t t a c h e d t o the e p i s t o m a l p l a t e ,  which i s i n t u r n  a p p a r e n t l y connected a n t e r i o r l y to the d o u b l u r e ,  the  two t o g e t h e r occupying the w i d t h of the r i m at the  axis'.  The most important diagnostic f e a t u r e  is  o f Paedeumias  t h e " s t a l k e d attachment of the hypostoma to the e p i s t o m a l plate,  o f t e n i n d i c a t e d d o r s a l l y by a narrow a x i a l r i d g e  a c r o s s the b r i m . I f the e p i s t o m a l p l a t e  of a l l members of  O l e n e l l u s and Paedeumias l i e s d i r e c t l y under the r i m , and the hypostoma no f u r t h e r forward than under the f r o n t a l g l a b e l l a r l o b e , s i n c e the two must be t h r e e c o n d i t i o n s can govern the mechanics of I f the r i m Is adjacent  attached, attachment.  to the f r o n t a l l o b e the hypostoma  and e p i s t o m a l p l a t e may be a t t a c h e d d i r e c t l y ; d i s t a n c e between f r o n t a l lobe and rim. i s  /  If  the  increased,  16. e i t h e r the p l a t e and r i m must be p r o p o r t i o n a t e l y wider f o r d i r e c t attachment,  o r , i f the p l a t e remains narrow  a s t a l k e d attachment must d e v e l o p .  Concerning Paedeumias,  Resser and Howell (1938, p . 226) s t a t e : "The hypostoma i s a t t a c h e d t o the m a r g i n a l , or more l i k e l y , e p i s t o m a l p l a t e , by a s t a l k whose l e n g t h equals the d i s t a n c e from the g l a b e l l a t o the r i m . " Observations The e p i s t o m a l p l a t e s  of 0 . e a g e r e n s l s  0 . s c h o f i e l d l have not been observed w i t h any  and certainty.  That of w. waleottana i s s l i g h t l y narrower than the r i m , w i t h hypostoma i n d i r e c t c o n n e c t i o n .  Denticulation  has been observed on only one hypostoma w i t h a s m a l l Paedeumias.  associated  No s e r r a t i o n s or t e e t h have  been seen, on any hypostomae of Wanner la, wale ot t a n a , although the e p i s t o m a l p l a t e o f t h i s t r i l o b i t e i s prominently d e n t i c u l a t e as t h a t o f the Two v e r y p e r f e c t gilbert!,  as  holotype.  s h i e l d s of O l e n e l l u s of  although l a c k i n g the hypostoma, r e t a i n the  e p i s t o m a l p l a t e s l i g h t l y drawn back from the r i m . way from the g e n a l angle to the c e n t r e the p l a t e  Halfis  about h a l f the w i d t h o f the r i m , widening to one r i m w i d t h a t the a x i s . . the p l a t e  At t h i s p o i n t a narrow s e c t i o n of  i s m i s s i n g (see F r o n t i s p i e c e ) .  i s about twice the width of the r i m .  The b r i m here  On a second specimen  IT. the. p l a t e  Is unbroken, and a widened p o r t i o n a t  the  a x i s i s s l i g h t l y l o n g e r than the m i s s i n g p a r t i n the first. I f the o r i g i n a l p o s i t i o n of the p l a t e  was  d i r e c t l y under the r i m , and t h e widened or m i s s i n g p a r t r e p r e s e n t s the attachment  of the hypostoma,  such  attachment must have been narrower than l o n g , i n o t h e r words a s t a l k .  T h i s i n f e r e n c e cannot be confirmed  a t present,^ s i n c e no s t a l k has been d i r e c t l y The e p i s t o m a l p l a t e  observed?.  of o l e n e l l i d s seems t o  have been hooked or anchored i n some way a t the p o s t e r i o r ends,  jU3t i n s i d e the genal a n g l e .  F l a t t e n i n g of  the  cephalon d u r i n g f o s s i l i z a t l o n would p u l l the ends a p a r t , g i v i n g r i s e t o the observed drawing back o f the  plate  from i t s o r i g i n a l p o s i t i o n at the r i m . THORAX I n most o l e n e l l i d s the a x i a l spine of the t h o r a c i c segment i s v e r y large'.  15th  But the o v e r a l l a s p e c t  of the thorax of O l e n e l l u s and p a r t i c u l a r l y of Paedeumias i s dominated by the extreme enlargement of the  third  p l e u r a l segments, extending i n t o s l e n d e r spines . 1  The shape of the t h o r a x , ' "wide" o r "narrow" o f a u t h o r s , i s compounded o f s e v e r a l v a r i a b l e s :  width  o f a x i a l and of p l e u r a l l o b e s , r e l a t i v e b o t h t o each  13 o t h e r and to t h e i r l e n g t h , and t o a c e r t a i n extent the degree of l a t e r a l or l o n g i t u d i n a l  compression and  f l a t t e n i n g subsequent t o b u r i a l . The main, c e n t r a l p a r t s of the carapace were r i g i d and more or l e s s b r i t t l e , even when the t r i l o b i t e was  a l i v e , but i t i s probable t h a t the f a l c a t e t i p s o f  the p l e u r a e were l e s s so.  Consequently, t h e degree of  f l e x u r e of these t i p s , e i t h e r b e f o r e or a f t e r b u r i a l , i s d l a g n o s t i c a l l y of l i t t l e v a l u e .  But the sharp or g r a d u a l  a n g l i n g back of p l e u r a e a t a p o i n t p r o x i m a l from the o u t e r t i p o f the p l e u r a l groove may distinguishing  specimens.  f r e q u e n t l y a i d In  F o r i n s t a n c e , the p l e u r a e of  Q« e a g e r e n s i s u s u a l l y angle back s h a r p l y , whereas those of Paedeumias and most s p e c i e s of O l e n e l l u s tend t o swing back more g r a d u a l l y . I n some s p e c i e s the r e l a t i v e l e n g t h of p l e u r a l groove to f a l c a t e t i p reduces u n i f o r m l y from f r o n t to back, as i n W. waleottana (Wanner, 1901, p.  267).  In t h i s s p e c i e s , where the t i p s a r e not unduly extended i n t o s p i n e s , the r a t i o may be used as an i n d i c a t i o n of the  "number" of segment from which an i s o l a t e d complete  p l e u r o n might have come, p e r m i t t i n g a rough e s t i m a t e to be made o f the s i z e o f o r i g i n a l s h i e l d . But the r e l a t i v e l e n g t h o f a s e l e c t e d p l e u r a l groove may  a l s o be compared between s p e c i e s as a  i9; diagnostic  aid.  I f the second p l e u r o n , which i s  q u e n t l y p r e s e r v e d and e a s i l y  identifiable,  is  fre-  examined,  the r a t i o of l e n g t h of p l e u r a l groove to w i d t h of lobe i s reasonably constant f o r a p a r t i c u l a r  axial  species,  •This r a t i o i s i n the o r d e r of 5:4 i n Paedeumias and i n most s p e c i e s 0'.  of O l e n e l l u s , but o n l y about 3:4 i n  eagerensis.  POST-OCULAR NODES P o s t - o c u l a r nodes i n o l e n e l l i d s have b r i e f l y r e f e r r e d t o by a number of authors,, smooth mounds, u s u a l l y e l l i p t i c a l , cheeks back o f ,  and i n s i d e o f ,  H o w e l l , 1 9 3 8 , pm 225) « :  been  They are  " . . . o n the  fixed  the eyes" (Resser and  On O l e n e l l u s and Paedeumias  they seem to be b e s t developed i n those p a l p e b r a l l o b e s are some d i s t a n c e  species  from the  whose  posterior  cephalic margin. On 0 . s c h o f l e l d i the p o s t - o c u l a r nodes are p a r t i c u l a r l y prominent, e v e n l y the  s l o p i n g up and back from  J u n c t i o n of the d o r s a l and p a l p e b r a l furrows  maximum e l e v a t i o n o p p o s i t e lobe|.  the r e a r of the 3 r d g l a b e l l a r  At t h i s p o i n t they drop away s t e e p l y  o p p o s i t e the o c c i p i t a l furrow. o t h e r hand, possesses  to  to  0 . eagerensis,  disappear on the  l o n g narrow p o s t - o c u l a r mounds of  f a i r l y even height- ( P l . I Fig.4) extending a l o n g the  side  of the d o r s a l furrow from i n s i d e the p a l p e b r a l lobe  to  j u s t back of the o c c i p i t a l furrow'.  20 At t h i s stage i n the r e s e a r c h , no f u n c t i o n may d e f i n i t e l y be a s s i g n e d t o p o s t - o c u l a r nodes o r mounds.  But i t seems reasonable  have some anatomical hypothesis  t o assume t h a t  explanation.  they  As a f i r s t working  i t i s suggested t h a t they r e p r e s e n t the  v e n t r a l "housing"  f o r p a i r e d organs, p o s s i b l y o v a r i e s ,  perhaps d i g e s t i v e glands,  or b o t h .  I f they a r e u l t i m a t e l y  proven to r e f l e c t i n t e r n a l anatomy they may w e l l be o f g r e a t e r taxonomic v a l u e than has h i t h e r t o been thought. ORNAMENTATION Surface ornamentation i s n o t an  important  c h a r a c t e r i s t i c g e n e t i c a l l y , b u t c e r t a i n s p e c i e s may e x h i b i t unique markings which are diagnostic'.  Thus, by  means of the r e t i c u l a t e s u r f a c e ornamentation "even a s m a l l fragment can be a s s i g n e d t o Wannerla" and Howell, 1938, p. 246).  (Resser  T h i s type o f p o l y g o n a l  pattern  has been observed on the d o r s a l s u r f a c e of a l l the l a r g e r specimens o f W. walcottana The  i n the c o l l e c t i o n .  cheek s u r f a c e o f O l e n e l l u s s c h o f l e l d l  is  u n l i k e t h a t o f any other form i n the c o l l e c t i o n , b u t consists of a pattern of r a d i a t i n g , i r r e g u l a r l y inosculating, raised l i n e s , reminiscent leaf.  According  of the v e i n p a t t e r n o f a  t o Lochman (1947, p« 61) t h i s  i s n e i t h e r ornamentation nor d i a g n o s t i c ;  venation  21  "... but r a t h e r i t appears to be the Impress of an i n t e r n a l anatomical s t r u c t u r e on the carapace. As i t has been observed i n many a p p a r e n t l y u n r e l a t e d genera r a n g i n g through the P a l e o z o i c , I t i s c o n s i d e r e d to be a f e a t u r e c h a r a c t e r i s t i c of the whole c l a s s . " Ornamentation such as t h a t f i g u r e d by Waleott (1910) on 0. g i l b e r t l has on any  specimens h e r e .  not been observed  However one  incomplete cephalon  of 0 . ef... g i l b e r t l e x h i b i t s an i r r e g u l a r r a i s e d f e r r u :  ginous network of a d i f f e r e n t k i n d .  Although the w r i t e r  t h i n k s t h a t t h i s has an i n o r g a n i c e x p l a n a t i o n ,  t h a t of  d e n d r i t i c p r e c i p i t a t i o n i n a narrow f i s s u r e , i t s development may chemical  have been determined by the  i n f l u e n c e of an o r i g i n a l s u r f a c e The p a t t e r n of o v e r l a p p i n g  of pleurae  of O l e n e l l u s h a l l l  ornamentation.  l i n e s on the  show them to be  t r a n s v e r s e on the v e n t r a l s u r f a c e but  l o n g i t u d i n a l on the d o r s a l .  sub-  This r u l e appears to  t o a l l the s p e c i e s of Wannerla, O l e n e l l u s and i n the G a r r e t t  tips  (Waleott) f i g u r e d by  Waleott (1910, p i . 31, f i g s . 10, 11) roughly  differential  apply  Paedeumias  collection.  GROWTH STAGES One  of the most important phases of palaeon-  t o l o g i c a l r e s e a r c h , a f t e r the p u r e l y d e s c r i p t i v e work has been done, i s the a n a l y s i s of o b s e r v a t i o n s .  Relation-  22 s h i p s between groups are sought, and e f f o r t s made t o disentangle  evolutionary trends.  The g r e a t e s t use,  both  economic-and p u r e l y s c i e n t i f i c , can be made of informat i o n only when i t s l i m i t a t i o n s a r e known. The  study o f perhaps g r e a t e s t taxonomic  v a l u e i n paleozoology of the most widely  i s t h a t o f growth stages,  f o r one  a c c e p t e d - p r i n c i p l e s has been the  b i o g e n e t i c law; "Ontogeny r e c a p i t u l a t e s Phylogeny". The  growth stages  have been s t u d i e d (Walcott,  o f only a few o l e n e l l i d s 1910).  But the e x t e n t t o  which t h e o r i e s o f e v o l u t i o n have been developed from such s t u d i e s i s b e s t i l l u s t r a t e d by r e f e r e n c e t o Raw (1925, 1927, 1936, 1937). accepted  w i t h some c a u t i o n .  But such t h e o r i e s should be I t i s possible that a  t r i l o b i t e d i d n o t s t a r t t o s e c r e t e h a r d p a r t s capable of f o s s i l i z a t i o n u n t i l ^ l t s development was so f a r advanced as t o p r o v i d e relationships.  only d o u b t f u l c l u e s as t o i t s  Furthermore, some of the ontogenies des-  c r i b e d i n the p a s t may have been based on i n s u f f i c i e n t specimens. Enough m a t e r i a l i s present  i n this  collection  t o warrant f u r t h e r work, b u t t h e w r i t e r r e g r e t s the l a c k o f time t o complete i t h i m s e l f . An i n t e n s i v e study should be made of the growth  23. stages of,.Paedeumias  and O l e n e l l u s i n t h i s  collection,  w i t h a view t o c o n f i r m i n g or c o n t r a d i c t i n g the c o n c l u s i o n s reached "by Waleott  (1910)  i n s o f a r as  they  apply to the fauna of the Eager F o r m a t i o n . PRESERVATION The O l e n e l l u s fauna i s n e a r l y always comparat i v e l y well preserved.  Apart from the c r u s h i n g of v e r y  t h i n , convex t e s t s , which i s to be expected even under the b e s t c o n d i t i o n s , the f i n e extremely f r a g i l e  sediments tend to  types of Crustacea  such as  preserve  the  homopods T u z o l a and Anomalooarls, and to f a v o r  the  r e t e n t i o n of c o n s i d e r a b l e d e t a i l i n the o l e n e l l i d s  them-  selves. The degree  of p r e s e r v a t i o n has a v e r y  b e a r i n g on taxonomy.  Removal of d i a g n o s t i c  d i s t o r t i o n of s t r u c t u r e s ,  real  details,  and even the s u p e r i m p o s i t i o n  of secondary c h a r a c t e r i s t i c s  of i n o r g a n i c o r i g i n , may  a l l p l a y t h e i r p a r t i n making i d e n t i f i c a t i o n and c l a s s i fication  difficult. I n the m a t e r i a l s t u d i e d h e r e , a t t e n t i o n  been drawn t o the almost complete absence In t h i s connection, segments  of 0 .  the 4 t h or 5 t h ,  it  is regrettable  eagerensis  pygldia.  t h a t the  thoracic  are seldom p r e s e r v e d b e h i n d  and no p l e u r a l segments  been found at a l l .  of  has  of Bonnla have  I t may be t h a t the apparent  absence  24. of i n t e r g e n a l s p i n e s i n l a r g e r specimens of i s a matter of incomplete  Paedeumias  preservation.  The extent of d i s t o r t i o n i n specimens often very d i f f i c u l t  to estimate.  It  is  is  reasonable,  t o assume t h a t v a r i a t i o n s from a common "mean shape" existed  i n every c o n s p e c i f i c  only one r e c o g n i z a b l e  t r l l o b i t e population.  s p e c i e s were p r e s e n t ,  If  the v a r i a -  t i o n s around the mean would f o l l o w a normal d i s t r i b u t i o n c u r v e , w i t h only one maximum p o i n t . the course of b u r i a l , shearing stresses, conceivably  However,  compaction and s u b j e c t i o n  to  o r i g i n a l l y I d e n t i c a l forms might  yield i n a definite  perhaps by the type of b a s i c  number of ways, l i m i t e d  structure.  This could give  r i s e to a s i m i l a r l y l i m i t e d number of " t y p e s " .  It  i s possible that  of  trilobltes  some o f the r e c o g n i z e d s p e c i e s  owe t h e i r s p e c i f i c  t i o n of mainly i n o r g a n i c  course of f l a t t e n i n g ,  stature  t o such a combina-  circumstances.  The convex c e p h a l i c  y i e l d more e a s i l y  because  s h i e l d of an o l e n e l l i d i n i t i s wider than l o n g , may  along the a x i s than l a t e r a l l y .  are most l i k e l y t o develop where g r e a t e s t t e n s i o n effective.  in  Such a p o i n t appears t o e x i s t  margin at the c e n t r e .  Subsequently,  at the  Cracks is frontal  the c r a c k would  extend backward over the cephalon, p e r m i t t i n g maximum  25. v e r t i c a l movement along the l i n e o f maximum c o n v e x i t y , t h a t I s , along the g l a b e l l a .  Once the two h a l v e s were  independent the next p o i n t o f maximum t e n s i o n would appear t o l i e a t o r near the base of the p a l p e b r a l l o b e . In t h i s way i t i s p o s s i b l e t o account f o r the commonly observed c e p h a l i c c r a c k s :  the primary f r a c t u r e o c c u r r i n g  along the a x i s , the secondary p a i r f o r t u i t o u s l y t i n g the a n t e r i o r branch o f the f a c i a l  simula-  suture.  Compression a c t i n g i n the s o l i d rock may be q u i t e i n t e n s e , and i t s m a n i f e s t a t i o n i n f o s s i l s can sometimes a f f o r d a measure o f I t s degree.  Several  specimens i n the c o l l e c t i o n show two o r more cephala, d i f f e r e n t l y o r i e n t e d , which e x h i b i t d i s t o r t i o n .  I n some,  the l e n g t h t o width r a t i o s d i f f e r from each other by as much as 40^.  Pure compaction, on the o t h e r hand may  l e a d to f a l s e length-width  r a t i o s due. t o t h e more i n t e n s e  l a t e r a l than l o n g i t u d i n a l y i e l d i n g of h e m i - c y l i n d r i c a l s t r u c t u r e s such as the a x i s and g l a b e l l a . Not  a l l notes on p r e s e r v a t i o n a r e gloomy..  One  n a t u r a l c a s t of O l e n e l l u s c f . g i l b e r t 1 ( P l . I I Fig.10) shows two shallow, forward  g e n t l y curved d e p r e s s i o n s  tapering  a c r o s s the cheek from t h e i r o r i g i n „.at_the base  of the p a l p e b r a l l o b e s . t o preclude  T h e i r p o s i t i o n and w i d t h appear  c o n f u s i o n w i t h " f a c i a l s u t u r e s " , y e t they  are almost c e r t a i n l y o f anatomical  significance.  Although  2&. a p p a r e n t l y unsegmented,  they are thought t o he t h e  Impressions o f a n t e n n u l e s . t h a t o f Dunbar, who s t a t e d  T h i s o b s e r v a t i o n confirms (1925, p.. 306) t h a t  antennae* " o f O l e n e l l u s " . . . a r e s i m p l e , p r o j e c t 1  the forward,  and show no evidence o f segmentation". CEPHALIC AND THORACIC RATIOS Because so many t r i l o b i t e s are d i s t o r t e d i t i s often i m p o s s i b l e t o gauge the o r i g i n a l shape o f a s i n g l e specimen.  S i m i l a r i t y o f shape depends upon s i m i -  l a r p r o p o r t i o n s o f component p a r t s .  On a d i s t o r t e d  specimen the. r a t i o o f l e n g t h t o w i d t h may be v e r y m i s l e a d i n g ; but the r e l a t i v e v a l u e o f measurements made i n the same d i r e c t i o n tends t o be constant f o r a s p e c i e s regardless of d i s t o r t i o n . Working i n d e p e n d e n t l y ,  the w r i t e r found t h a t  c e r t a i n c e p h a l i c r a t i o s were o f d i a g n o s t i c v a l u e : o v e r a l l w i d t h o f the cephalon t o t h a t o f the  the  occipital  r i n g , and the l e n g t h o f the o c c i p i t a l and t h r e e  lobes  immediately a n t e r i o r t o i t r e l a t i v e t o t h a t o f the p a l pebral  lobes. L a t e r , : t h i s system was m o d i f i e d t o b r i n g i t  i n t o l i n e w i t h the methods suggested by Lochman (1947, p . 60).  The c e p h a l i c f e a t u r e s •1  1. S i c  finally u t i l i z e d i n this  27 c o n n e c t i o n were: 1.  R e l a t i v e p o s i t i o n o f midpoint of eye to t h a t of g l a b e l l a . ( I b i d )  relative  1  2 . Width o f cheek from d o r s a l furrow t o o u t s i d e of genal angle r e l a t i v e t o width o f o c c i p i t a l ring. ( I b i d , modified f o r o l e n e l l i d s ) 3. Length of r e a r f o u r c e p h a l i c l o b e s , i n c l u d i n g the o c c i p i t a l , t o t h a t of p a l p e b r a l l o b e s . 4 . F o r the sake of completeness, the t h o r a c i c r a t i o , l e n g t h o f p l e u r a l groove t o w i d t h of a x i a l lobe a t the 2nd segment, i s I n c l u d e d here • TABLE I C e p h a l i c and T h o r a c i c R a t i o s Average v a l u e s of 10 t y p i c a l - specimens of each s p e c i e s Species: 1 2 3 4O l e n e l l u s eagerensis level 1.0-1.25 1.5-1*8 0.6-0.8  0. s c h o f i e l d l 0. cf. .gilbert!  behind  Paedeumias nevadensis  " l'  1.8-1.9 1.6-1>7 1.7-1.9  (numbered columns r e f e r to s e c t i o n s  1.4-1.8 1.2-1.3 1.25-1.35 1.1-1'.2 1.25-1.35 D.l-1.2 In the t e x t )  SYSTEMATIC POSITION OF OLENELLIDS The f a c i a l suture as such does n o t appear t o be p r e s e n t  in olenellids.  marginal sutures.  But most o f them do possess  The w r i t e r i s i n c l i n e d t o agree  with  the f o l l o w i n g statement by Swinnerton (1919, p. 103): " T r i l o b i t e s i n common w i t h a l l o t h e r Arthropods shed t h e i r more o r l e s s r i g i d e x t e r n a l c o v e r i n g or e x o s k e l e t o n p e r i o d i c a l l y . To accomplish t h i s ecdysis. i t i s n e c e s s a r y f o r t h i s c o v e r i n g t o s p l i t somewhere; and i t  28.  -  i s h i g h l y probable that the-.facial suture was t h e l i n e a l o n g w h i c h s u c h - s p l i t t i n g took place. T h e r e seems however t o b e a t e n d e n c y t o assume t h a t a l l l i n e s w h i c h s e r v e d t h i s purpose are homologous. This has i n t r o d u c e d u n n e c e s s a r y d i f f i c u l t i e s i n t o t h e study o f T r i l o b i t e c l a s s i f i c a t i o n . " Since  t h e a c c e p t e d method o f c l a s s i f i c a t i o n  does i n v o l v e  facial  sutures  with Poulsen  (1932)  and Resser  tion an  i t seems w i s e s t  (1938)  o f t h e o l e n e l l i d s and t o a c c o r d  order.  Because O l e n e l l u s .  g e n u s , a n d one o f t h e  unique  posi-  them t h e r a n k o f  as t h e f i r s t  described  most w i d e l y d i s t r i b u t e d , a p p e a r s  t o be f i r m l y e s t a b l i s h e d a s t y p i c a l , followed  the  t o admit  here includes  the c l a s s i f i c a t i o n  these t r i l o b i t e s  i n the  order  Olenelllda.  GENERIC AND S P E C I F I C  DISTINCTIONS  Resser and Howell genotypes o f O l e n e l l u s  (1938)  state  that  a n d M e s o n a c l s . 0.  M. v e r m o n t a n a do n o t show s u f f i c i e n t  since the  Thompson! a n d  differences, the  names " M e s o n a c l s " a n d " M e s o n a c i d a e " must b e d r o p p e d . point  o u t t h a t the  d i f f e r e n c e between the  segments o f t h e s e s p e c i e s  importance".  (Ibid. p.  Since  posterior  " e x i s t s a n d h a s some  c a n c e , b u t i t i s n o t now b e l i e v e d  They  signifi-  t o be o f generic  217)  thepoor and infrequent  preservation of  29. t e r m i n a l segments has. l e d i n the p a s t t o so. much confusion,  i t i s c l e a r t h a t they cannot c o n s t i t u t e the  p r i n c i p a l c r i t e r i o n f o r generic d i s t i n c t i o n .  Other  c r i t e r i a , based upon d i f f e r e n c e s i n t h e cephalon and thorax must be used a l s o .  I t i s believed that  suffi-  c i e n t d i f f e r e n c e e x i s t s between c e r t a i n s p e c i e s of O l e n e l l u s t o j u s t i f y r e - e x a m i n a t i o n of the problem. I f "Mesonacls" were r e s t r i c t e d o n l y t o such comparatively  d i s t i n c t s p e c i e s as 0. e a g e r e n s i s ,  M.  i n s o l e n s , M. b r i s t o l e n s i s . and perhaps 0. vermontanus, a majority  o f the f o l l o w i n g c r i t e r i a might d i f f e r e n t i a t e  such a genus from O l e n e l l u s o r from Paedeumias. s i n c e the w r i t e r i s dependent specimens from other  But,  on photographs r a t h e r than  l o c a l i t i e s , t h i s proposal  i s made  very tentatively'. TABLE I I  a. b. c. d. e. f. g. h. 1.  P o s s i b l e Generic D i s t i n c t i o n s Characteristic Paedeumias O l e n e l l u s Mesonacls P o s t e r i o r .segments . "4 ~~ 2-6 . 10 • Centres: eye t o g l a b e l l a (1. p . 27) ' behind behind level L a t e r a l cephalic r a t i o ..(2-, p. 27) 1.6-1.9 1.8-1.9 1.0-1.25 Longitudinal cephalic . r a t i o (3, p . 27) 1.2-1.4 1.2-1.8 1.5-1.8 Lateral.thoracic ratio .(4, p . 27) 1.0-1.2 1.2-1.3 0.6-0.8 G l a b e l l a r shape c y l i n d r i c a l c y l i n d r i c a l "hourMay t a p e r . .glass" forward Brim, a n t e r i o r t o . glabella always sometimes never S t a l k on hypostoma always never never I n t e r g e n a l spines always frequently reduced  30. RECOMMENDATIONS FOR FURTHER STUDY 1.  A study s h o u l d be made of the growth stages of O l e n e l l u s and Paedeumias i n the G a r r e t t c o l l e c t i o n ,  2. I t i s p o s s i b l e t h a t two subspecies o f O l e n e l l u s e a g e r e n s i s are p r e s e n t , one w i t h narrower cheeks, the other w i t h a more e n l a r g e d f r o n t a l l o b e , than t h a t described i n t h i s paper. T h i s s h o u l d be checked, 3» As i n d i c a t e d by Walcott (1910), Resser (1928) and as observed by t h e . w r i t e r , i t i s possible that Olenellus g i l b e r t ! i s a '"form s p e c i e s " c o m p r i s i n g l e g i t i m a t e s p e c i e s of Paedeumias.as w e l l as O l e n e l l u s , Resser ( I b i d . p . -9) states^: " i t seems c e r t a i n . . . t h a t some of the specimens r e f e r r e d by authors to Mesonacls g i l b e r t ! b e l o n g n e i t h e r to t h a t s p e c i e s nor even t o M e s o n a c l s . but are d i s t i n c t s p e c i e s of Paedeumias." This s p e c i e s should be thoroughly re-examined, 4 . As i n d i c a t e d i n t h i s p a p e r , i f the g e n e r i c d i s t i n c t i o n s o u t l i n e d by Lochman (1947, p . 60) are f o l l o w e d , a t l e a s t one.new genus must be e r e c t e d on the b a s i s of c e p h a l i c c h a r a c t e r i s t i c s . (See p . 29) T h i s may i n v o l v e the r e - e x a m i n a t i o n . o f g e n e r i c d i s t i n c t i o n s a n d . r e c l a s s i f i c a t i o n of the whole order O l e n e l l l d a .  31. CHAPTER I I I DESCRIPTION OF GENERA-AND SPECIES Phylum Class Subclass Order Family  Arthropoda Crustacea Triloblta Olenelllda Olenellidae  Genus  Olenellus  Hall,  1862  N.Y. S t a t e Cab. Nat. H i s t . , 13th Rept. (1860) p. 115. N.Y. S t a t e Gab. Nat. H i s t . , 15 Rept. (1862) p. 114. Am. J o u r . S c i . , 3rd s e r . , v o l . 29, (1885) p. 328, f i g . 1, 2. U.S. G e o l . Surv., B u l l . 30, (1886) p. 162, I 6 5 . U.S. G e o l . Surv., B u l l . 30, (1886) p. 158, 165. U.S. G e o l . Surv., 10th Ann. Rept.  Barrandia  Hall  Olenellus  Hall  Mesonacls Olenellus  Walcott . Walcott  Mesonacls  Walcott  Olenellus  Walcott  Mesonacls  Walcott-U.S. G e o l . Surv., 10th Ann. Rept. (1891) p. 637. Walcott Smithsonian M i s c . C o l l . , V o l . 53, no. (1910) p. 246, 261. Walcott Smithsonian M i s c . C o l l . , v o l . 53, no. (1910) p. 248, 311. Resser Smithsonian M i s c . C o l l . , v o l . 81, no. (1928) p. 3 . Resser Smithsonian M i s c . C o l l . , v o l . 81, no. (1928) p. 5 . Resser and Howell, B u l l . G e o l . Soc. Amer., v o l . 49, (1938) p. 217, 218.  Mesonacls Olenellus Mesonacls Olenellus Olenellus  (1891) p. 165,-633.  6 6 2 2  The most r e c e n t a u t h o r i t a t i v e work on o l e n e l l i d s i s t h a t by Resser and Howell  (1938).  U n t i l a great deal  more much needed study has been made of the whole o r d e r it  i s - c l e a r t h a t t h e i r g e n e r i c diagnoses of O l e n a l l u s and  Paedeumias. must stand as p a r t i a l c l a r i f i c a t i o n of what  32. had been taxonomic chaos. But the w r i t e r , f a c e d w i t h a fauna i n which c e r t a i n s p e c i e s a s s i g n e d to O l e n e l l u s show c l o s e r a f f i n i t i e s t o Paedeumias than to other s p e c i e s p l a c e d i n t h e i r own grouping.  genus, i s bound t o suggest a l t e r n a t i v e  I t i s probable  t h a t e i t h e r a r e s t r i c t e d genus  Mesonacls w i l l have t o be r e v i v e d , or t h a t the genus Paedeumias. w i l l have t o be g r e a t l y e n l a r g e d a t the pense of O l e n e l l u s ; expedients  w i l l be The  indeed;  ex-  i t i s p o s s i b l e that both  ne c e s s a r y .  f o l l o w i n g g e n e r i c d i a g n o s i s of O l e n e l l u s  i s summarized and Howell (1938, p.  slightly  m o d i f i e d from Resser  and  217).  Diagnosis The  cephalon i s l a r g e ; the thorax,  segments, i s l o n g and  of many  t a p e r i n g ; the pygidium i s r e p r e -  sented by a s m a l l p l a t e . Cephalon u s u a l l y s e m i c i r c u l a r , h i g h l y convex, w i t h l o n g genal s p i n e s .  F a c i a l sutures not f u n c t i o n a l .  G l a b e l l a wide, extending  to f r o n t a l rim, e i t h e r c y l i n -  drical  or "hourglass"  g l a b e l l a r furrows,  shaped.  the f i r s t  Of the t h r e e p a i r s of connects a c r o s s the middle,  s e t t i n g o f f the rounded f r o n t a l l o b e ; the second i s f r e q u e n t l y reduced to a p a i r of s l i t s , which i n a d u l t s  33.  fail  to reaoh the d o r s a l furrow; the t h i r d p a i r o f  furrows,  l i k e the o c c i p i t a l b e h i n d i t ,  a c r o s s the g l a b e l l a .  fails  to  connect  The d o r s a l furrow i s deep,  but  i n t e r r u p t e d by the j u n c t i o n o f the f r o n t a l and p a l p e b r a l lobes.  The brim i s narrow, o f t e n only e q u a l t o the  w i d t h of the m a r g i n a l furrow. between s p e c i e s ,  Rim v a r y i n g i n w i d t h  u s u a l l y f a i r l y narrow, widening  toward the genal a n g l e s .  slightly  P a l p e b r a l lobes s e m i c i r c u l a r ,  separated from the g l a b e l l a by the d o r s a l furrow (and p o s t - o c u l a r nodes i f p r e s e n t ) .  Eyes l a r g e a n d , l i k e  the p a l p e b r a l l o b e s , may extend almost t o the p o s t e r i o r margin.  F a c i a l sutures are not p r e s e n t as s u c h , but  p o s s i b l y are r e p r e s e n t e d p o s t e r o - l a t e r a l l y by r a i s e d , sometimes asymmetrical and b i f u r c a t i n g l i n e s , r u n n i n g from under the eyes toward the g e n a l a n g l e s . are l a r g e and convex.  Intergenal  spines o f t e n  Cheeks present.  Genal spines u s u a l l y l a r g e , but s m a l l e r when i n an advanced p o s i t i o n . Hypostoma s t r o n g l y convex,  about the same  as the f r o n t a l l o b e , a t t a c h e d d i r e c t l y t o a n a r r o w  size  j  e p i s t o m a l plate'* T h o r a c i c segments v a r y i n g i n number, but within a single  species,  u s u a l l y loosely arranged.  fixed Pleurae  54. straight,  s h a r p l y c u r v i n g back to l o n g t a p e r i n g  P l e u r a l grooves wide and s t r a i g h t where they bend s l i g h t l y  less  ends.  t o the f u l c r u m ,  s h a r p l y than the  pleurae,  and b e g i n to c o n t r a c t  s l i g h t l y more a b r u p t l y than the  p l e u r a l terminations*  The f u l c r a l angle and t a p e r e d  terminations  i n c r e a s e p o s t e r i o r l y i n p r o p o r t i o n to  the d e c r e a s i n g l e n g t h of the p l e u r a e .  The r e a r s e g -  ments p o i n t almost d i r e c t l y backward, p a r t l y the l a r g e a x i a l spine on the 15th  segment.  enclosing Varying  numbers of s m a l l segments p o s t e r i o r to the 15th  are  terminated by a p y g i d l a l p l a t e .  These segments are  o f t e n c a l l e d rudimentary because  they o f t e n l a c k p l e u r a l  extensions.  Except f o r the f i f t e e n t h  spines are u s u a l l y  segment,  axial  absent.  Surface may be i r r e g u l a r l y l i n e d . O l e n e l l u s i s most e a s i l y Paedeumias.  from which i t d i f f e r s  the p o s i t i o n and s i z e  confused w i t h "...chiefly  of the g l a b e l l a ,  d o u b l u r e , and i n the d i r e c t attachment to the marginal p l a t e , Paedeumias"  without  i n the  in wider  of the hypostoma  the s l e n d e r s t a l k  (Resser and H o w e l l , p . 2 1 8 ) .  Genotype:  O l e n e l l u s thomnsoni H a l l  1862  of  35  OLENELLUS o f ,  GILBERTI  MEEK,  Frontispiece; Plate I I ,  1874 Figs.  6-10.  T h i s i s one of the commonest, s p e c i e s i n the Eager F o r m a t i o n .  One of the b e t t e r  present  preserved  specimens i s i l l u s t r a t e d as the F r o n t i s p i e c e . From o b s e r v a t i o n s from statements  of 0 . c f .  g i l b e r t l and 226)  made by competent workers ( I b i d p .  i t may be i n f e r r e d t h a t the presence of a b r i m of c o n s i d e r a b l e width s e p a r a t i n g a narrow r i m from the g l a b e l l a i s i n d i c a t i v e of a s t a l k e d hypostoma.  If  this  i s so, many s p e c i e s now a s s i g n e d to O l e n e l l u s s h o u l d be t r a n s f e r r e d t o Paedeumias. f o r e c a s t by Waleott  Of t h e s e ,  0. g i l b e r t ! ,  as  (1910, p . 329) and by Resser  (1928, p . 9) should almost c e r t a i n l y be one of the However, s i n c e f u r t h e r s t u d y , specimens and of the e x c e l l e n t l y  first.  b o t h of the type  preserved f o s s i l s  from  the Eager Formation, i s p r e r e q u i s i t e t o such a s t e p ,  it  seems w i s e s t to take no c o n t r o v e r s i a l a c t i o n at t h i s  time.  Diagnosis Apart from the presence of a b r i m , whose w i d t h v a r i e s from e q u a l to twice t h a t of the r i m , the cephalon conforms t o g e n e r i c d e s c r i p t i o n . subdued or absent  Intergenal  spines  i n specimens l a r g e r than 15 mm i n w i d t h .  The shortness of the p a l p e b r a l l o b e s i s masked t o a c e r t a i n e x t e n t by long, low p o s t - o c u l a r mounds.  Marginal  36.  and i n t r a m a r g i n a l sutures p r e s e n t .  Rim  f a i r l y narrow,  but v a r i e s s l i g h t l y between i n d i v i d u a l s j i t widens f a i r l y s t r o n g l y a t the genal a n g l e s .  Epistomal p l a t e  the same width as r i m a t the f r o n t , t a p e r i n g g e n t l y toward the genal a n g l e s .  Small node or spine on pos-  t e r i o r of o c c i p i t a l l o b e . Pleurae of t h i r d t h o r a c i c segment g r e a t l y e n l a r g e d making n e a r l y a r i g h t angle a t the  fulcrum.  S i n g l e s m a l l spines on the p o s t e r i o r margins of a x i a l l o b e s are t r a c e a b l e forward, p r o g r e s s i v e l y r e d u c i n g i n s i z e from the 14th segment t i l l a t the 3rd.  they d i e out a l t o g e t h e r  The a x i a l spine on the 15th segment i s v e r y  l a r g e and l o n g , p r e s e n t i n g a c u r i o u s dimpled s t r u c t u r e ; the minute depressions are arranged i n quincunx. Rudimentary segments were v e r y d o u b t f u l l y observed t o be  on only one specimen; no l e s s than t h r e e appear  present. C e p h a l i c and t h o r a c i c r a t i o s are g i v e n i n  Table I . Relationships The most n e a r l y a l l i e d forms are those to O l e n e l l u s g i l b e r t l Walcott, Paedeumias (Walcott) and P. c l a r k i  Resser.  assigned  nevadensis  37. This species  differs  from 0 . g l l b e r t l  having s h o r t e r p a l p e b r a l l o b e s ,  and c e r t a i n  in  indications  of a s t a l k e d hypostoma.  From- P. c l a r k i i t d i f f e r s  p o s s e s s i n g a wider r i m .  From P. c l a r k i and P .  i t differs  in  nevadensls  i n having a narrower b r i m , a more expanded  f r o n t a l l p b e , and i n l a c k i n g i n t e r g e n a l s p i n e s when adult. OLENELLUS EAGERENSIS Plate I,  Figs,  n.  sp.  1-11*  The most s t r i k i n g f e a t u r e i s the g r e a t width o f the  of 0 .  eagerensis  axis'.  Cephalon i s s e m i c i r c u l a r i n f r o n t ;  posterior  margin w i t h c l e a r l y developed i n t e r g e n a l angle of 145°  i n adults,  l e s s c l e a r l y marked i n young  about  specimens.  Advanced, f a i r l y s m a l l genal s p i n e s , always o b l i q u e the a x i s by an angle  of about 2 0 ° .  shaped, w i t h s t r o n g l y lobe t o u c h i n g the r i m .  Glabella  "hourglass"  convex s e m i - e l l i p s o i d a l Both f r o n t p a i r s of  furrows i n a d u l t s reduced t o s l i t s ,  to  frontal  glabellar  the second almost  t o dimples; i n immature forms these two furrows  connect  a c r o s s the m i d d l e , but the second p a i r does not  extend  t o the d o r s a l furrow.  strongly  arched, i t s  t i p e x t e n d i n g t o j u s t b e h i n d the  g l a b e l l a r furrow. slightly  Palpebral lobe i s s h o r t ,  third  Rim i s v e r y narrow, widening  a t the genal a n g l e .  only  Posterior rim shallow,  38, widened a t the I n t e r g e n a l  angle.  Small i n t e r g e n a l  spines are sometimes f a i n t l y developed j u s t intergenal angles; t e d by a s l i g h t  even when absent,  outside  they are r e p r e s e n -  t h i c k e n i n g of the r i m , which i s  joined  by a low r i d g e t o the back of the p o s t - o c u l a r mounds o p p o s i t e the o c c i p i t a l f u r r o w . with a small p o s t e r i o r  O c c i p i t a l r i n g wide,  spine.  Thorax w i t h b r o a d a x i s . comparatively s h o r t ,  lobes  s h a r p l y a n g l i n g back and a b r u p t l y  t a p e r i n g to s h o r t s p i n e s . flat,  Pleural  P l e u r a l grooves  short, broad,  marked o f f d i s t i n c t l y b y . a r i m b o t h a n t e r i o r l y  and p o s t e r i o r l y . enlarged;  P l e u r a e of t h i r d segment not  Small a x i a l spines p r e s e n t on a l l  greatly  thoracic  segments a n t e r i o r t o the 1 5 t h ;  the l a t t e r  e n l a r g e d , but t a p e r s s h a r p l y .  Nothing i s known o f  ments,  or pygidium, p o s t e r i o r t o the  spine  is seg-  15th.  C e p h a l i c and t h o r a c i c r a t i o s are g i v e n  in  Table I . Holotype::  Department of Geology, U n i v e r s i t y of B r i t i s h Columbia, No. GT 1 0 1 . C o l l ; : C. G a r r e t t .  P a r a t y p e s : Department of Geology, U n i v e r s i t y , of B r i t i s h Columbia, Nos. GT 1 0 2 110. C o l l : : C . Garrett. Type L o c a l i t y : L o c . B. Eager F o r m a t i o n , 6 m i . N . E . of Granbrook, B . C . Geologic Age:  Lower Cambrian.  39.  Discussion T h i s s p e c i e s of O l e n e l l u s shows such s t r i k i n g d i f f e r e n c e s from the genotype, t h a t were the recommend a t i o n s o f Lochman (1947) f o l l o w e d , i t would  probably  be p l a c e d i n a d i f f e r e n t genus. I t s c l o s e s t a f f i n i t y to f i g u r e d s p e c i e s i s t o t h e drawings reproduced by Walcott (1910, p i . 37, F i g s . 8 - 1 9 ) from h i s p r e v i o u s p u b l i c a t i o n s (1884, 1886, 1 8 9 1 ) p u r p o r t i n g t o show the young stages of 0. f r e m o n t l .  o f growth  The l a t t e r s p e c i e s has been r e s t r i c t e d  by Resser ( 1 9 2 8 ) and proven not t o possess advanced genal  spines. 0. e a g e r e n s l s  i n having  d i f f e r s from Walcott's f i g u r e s  a narrower rim, s m a l l e r genal s p i n e s ,  a n t e r i o r l o b e , and wider, more evenly  shorter  tapering palpebral  l o b e s ; b u t i t s s i m i l a r i t y i s apparent i n view o f Walcott's own t e n t a t i v e i d e n t i f i c a t i o n of "0. o f . f r e m o n t l " from the Eager Formation ( S c h o f i e l d , 1 9 2 2 , p . 1 2 ) .  (Resser,  From "Mesonacls" b r l s t o l e n s i s and "M".  insolens  1 9 2 8 ) i t d i f f e r s i n h a v i n g l e s s advanced  genal  s p i n e s , wider i n t e r g e n a l angles, narrower r i m , and more rounded f r o n t a l l o b e . i n having  From 0. vermontanus i t d i f f e r s  s l i g h t l y s h o r t e r p a l p e b r a l l o b e s , narrower r i m ,  40. sharper i n t e r g e n a l a n g l e s ,  and a s l i g h t l y wider  cheek.  From o t h e r o l e n e l l i d s i n the c o l l e c t i o n the quoted d i f f e r e n c e s  are even more marked.  This species  i s w e l l r e p r e s e n t e d i n the  col-  l e c t i o n , and i s based on no l e s s than one hundred cephala r a n g i n g from 2.4 t o 35 mm. i n w i d t h . It it  i s named f o r the Eager Formation i n which  i s found.  OLENELLUS SCHOFIELDI Plate  I,  n.  sp.  Figs." 12-17.  Cephalon s e m i c i r c u l a r , s l i g h t l y i n elongated margin.  specimens,  trapezoidal  w i t h an almost s t r a i g h t  G l a b e l l a narrow, c y l i n d r i c a l , w i t h  posterior  expanded  h e m i s p h e r i c a l f r o n t a l lobe r e a c h i n g the r i m .  Glabellar  furrows normal f o r genus;  second p a i r reduced to  P a l p e b r a l l o b e s extremely  short,  to opposite  their tips  extending  the f r o n t h a l f of the 3rd g l a b e l l a r  behind the f r o n t a l . '  slit's.  lobe  P o s t - o c u l a r nodes v e r y prominent  and s h o r t , rounding down a b r u p t l y b e h i n d t h e i r  point  of maximum e l e v a t i o n opposite the back of the 3rd lobe.  glabellar  Rim v e r y narrow, h a r d l y widening a t a l l toward  the genal a n g l e . spines p r e s e n t ,  Genal s p i n e s s l e n d e r .  Intergenal  j o i n e d t o back o f p o s t - o c u l a r mounds by  41. a slightly raised ridge. may be  A minute o c c i p i t a l  spine  present. Thorax t y p i c a l o f the genus, but the  somewhat narrow a n t e r i o r l y , appears to t a p e r gradually.  Pleurae a n g l i n g back s h a r p l y t o  terminations.  axis,  rather slender  Third pleurae strongly enlarged.  Small  a x i a l spines are present on segments p o s t e r i o r to  the  fifth.-Rudimentary segments and pygidium unknown. V e n a t i o n of the cheek s u r f a c e  is  strikingly  developed on the l a r g e r forms, c o n s i s t i n g o f  radiating,  irregularly inosculating, raised lines. The l a r g e s t  cephalon a s s i g n e d to t h i s  i s 32.6 mm. wide by 17«1 mm. l o n g . to length (1.9) little  for this  species  The r a t i o of w i d t h  specimen i s b e l i e v e d t o be a  h i g h ; two other cephala o r i e n t e d almost  exactly  a t r i g h t angles y i e l d an average r a t i o of 1.8.  Other  c e p h a l i c and t h o r a c i c r a t i o s are g i v e n i n Table  I.  H o l o t y p e : Department of Geology, U n i v e r s i t y of B r i t i s h Golumbia No. GT 201. C o l l : C. G a r r e t t . Paratypes:  Department of Geology, U n i v e r s i t y of B r i t i s h Columbia, Nos. GT 202210. Ooll:.:C. Garrett.  Type L o c a l i t y : L o c . B , Eager F o r m a t i o n , 6 mi. N . E . of Cranbrook, B . C . Geologic Age:  Lower Cambrian.  42 Discussion The shortness o f p a l p e b r a l l o b e s , the p r o minent p o s t - o c u l a r nodes, the s t r o n g l y developed v e n a t i o n and extremely narrow r i m serve t o d i s t i n g u i s h 0.  s c h o f i e l d i ' f r o m a l l other c o r d i l l e r a n species. From 0 . b r e v o c u l u s i t i s d i s t i n g u i s h e d by  .  i t s having a narrower r i m and r e l a t i v e l y narrower g l a b e l l a , and from 0 . f r e m o n t l ( s . s . ) by the narrow r i m , s t r a i g h t p o s t e r i o r c e p h a l i c margin and p o s s e s s i o n o f intergenal spines. T h i s s p e c i e s i s comparatively r a r e , o n l y t e n specimens b e i n g d e f i n i t e l y a s s i g n a b l e t o i t i n t h i s collection.  I t i s named a f t e r S . J . S c h o f i e l d of the  G e o l o g i c a l Survey of Canada who f i r s t r e p o r t e d t h e p r e sence  o f o l e n e l l i d s near  GENUS PAEDEUMIAS WALCOTT  Cranbrook. 1910  Paedeumias Walcott, Smithsonian M i s c . C o l l . , v o l . 53, . no. 6 (1910 p . 304. Paedeumias Resser, Smithsonian M i s c . C o l l . , v o l . 81,  no. 2 (1928) p. 5  Paedeumias Resser and Howell, B u l l . G e o l . Soc. Amer.,  v o l . 49, no. 2 (1938) p . 225.  The r e d e s c r i p t i o n of t h i s genus by Resser- and Howell  (1938 p 225)  expresses t h e e s s e n t i a l  characteristics:  "The cephalon- i s l a r g e and broad, t h e thorax has many l o n g - s p l n e d segments and t e r m i n a t e s  43. i n a small p l a t e . The cephalon i s s e m i c i r c u l a r i n o u t l i n e , and probablyhad c o n s i d e r a b l e c o n v e x i t y . Facial s u t u r e s are sometimes t r a c e a b l e back of the e y e s . Glabella generally-cylindrical w i t h the a n t e r i o r l o b e t a p e r e d r a t h e r b l u n t l y , and s i t u a t e d some d i s t a n c e from the r i m . The d o r s a l furrows are w e l l impressed except where the eyes J o i n . Rim u s u a l l y narrow (never w i d e ) , i n c r e a s i n g b u t s l i g h t l y toward.the genal a n g l e s . A r i d g e connects the median p o i n t of the a n t e r i o r g l a b e l l a r l o b e w i t h the r i m , but i t i s p o s s i b l e t h a t t h i s f e a t u r e d i d not always show on the l i v i n g a n i m a l , r e s u l t i n g from compression of the test, on t o the" hypostoma.stalk during f o s s i l i z a t l o n . Eyes l a r g e , extending almost to t h e r e a r m a r g i n ; ! the o u t e r curved edge, and perhaps a l s o the r e a r p o r t i o n of the eye l o b e s , were r a i s e d f r e e above the cheek s u r f a c e s . Genal s p i n e s s l e n d e r , i n a d u l t i n d i v i d u a l s , extending t o about the t h i r d or s i x t h pleuron. I n t e r g e n a l spines p r e s e n t i n , a l l s p e c i e s now d e f i n i t e l y a s s i g n e d to the genus. 1  The hypostoma i s a t t a c h e d t o the m a r g i n a l o r , . m o r e l i k e l y , e p i s t o m a l p l a t e , by a s t a l k whose l e n g t h equals the d i s t a n c e from the g l a b e l l a t o the r i m . The hypostoma i t s e l f i s t y p i c a l f o r the f a m i l y , h a v i n g f i v e or more t e e t h oh each s i d e of the median l i n e . The p l a t e t o which the hypostoma i s a t t a c h e d f r e q u e n t l y breaks away, sometimes, i n such a manner as to i n d i c a t e a h i n g e d attachment between the g e n a l angles and the i n t e r g e n a l s p i n e s . Thorax a p p a r e n t l y has n i n e t e e n segments. The f i r s t f i f t e e n are normal i n shape, w i t h the t h i r d g r e a t l y e n l a r g e d . A l o n g heavy spine i s present on the f i f t e e n t h p l e u r o n . Back o f t h i s the Y o r k s p e c i e s shows f o u r r a t h e r simple segments and f i n a l l y a s m a l l pygidial plate. Small spines, i n c r e a s i n g s l i g h t l y i n s i z e r e a r w a r d , a r e p r e s e n t on the s i x or more segments immediately b e f o r e the f i f t e e n t h . 1  1.  Sic  44. Surface f a i n t l y l i n e d i n the u s u a l fashion, Paedeumias d i f f e r s l i t t l e from O l e n e l l u s except i n the p o s i t i o n o f the g l a b e l l a and the s t a l k e d hypostoma. Genotype;  P. t r a n s l t a n s w a l c o t t , 1910"  To the above d i a g n o s i s l i t t l e  can be added,  but the p a l p e b r a l lobes and eyes o f a t l e a s t one s p e c i e s , P. nevadensis. a r e s h o r t and extend no f u r t h e r back than the o c c i p i t a l furrow*  S i m i l a r l y the w r i t e r main-  t a i n s personal reservations concerning i n t e r p r e t a t i o n of  l i n e s back o f the eyes as f a c i a l sutures*.  PAEDEUMIAS NEVADENSIS (Walcott) 'Plate  I I , P i g s . 1-5.  "  '  O a l l a v i a ? nevadensis .Walcott, 1910 (pars) Smithsonian M i s c . C o l l . , v o l . . 5 3 , No. 6 p. 285, p i . 38, P i g . 12. paedeumias nevadensis Resser, (1928) Smithsonian M i s c . C o l l . , v o l . 81, No. 2, p . 9, p i . 3, F i g s . 3-7. The main s p e c i f i c c h a r a c t e r i s t i c s a r e :  the  b l u n t l y tapering g l a b e l l a , short p a l p e b r a l lobes, extend i n g no f u r t h e r than o p p o s i t e the o c c i p i t a l furrow, and wide brim, about 3 t o 4 times the w i d t h o f the r i m . P=*~nevadensis i s e a s i l y c o n f u s i b l e w i t h O l e n e l l u s c f . g i l b e r t ! i n the Eager Formation.  These  s p e c i e s a p p a r e n t l y o v e r l a p i n w i d t h o f brim, s i z e o f  45.  '  f r o n t a l and p a l p e b r a l l o b e s , and i n development of a x i a l and i n t e r g e n a l s p i n e s .  Furthermore,  the Immature  specimens i n the c o l l e c t i o n are p r a c t i c a l l y a l l o f the Paedeumias type, and a t t h i s stage i n the r e s e a r c h c o u l d , w i t h e q u a l f a c i l i t y , be r e f e r r e d t o 0. o f . K l l b e r t l . P. nevadensis. o r i n some cases t o P~. c f . clarki. T h i s g i v e s p o i n t t o the s u g g e s t i o n t h a t these forms, i f n o t c o n s p e c i f i c ; a r e here i n t h e p r o c e s s of separating into d i s t i n c t species.  I t i s believed that  a thorough s t a t i s t i c a l a n a l y s i s , based on s e v e r a l f e a t u r e s , i s necessary t o check t h i s s u g g e s t i o n . GENUS WANNERLA  WALCOTT, 1910  Wannerla Waleott. Smithsonian Mlso. C o l l . , v o l . 57, No. 6 (1910) p . 248, 296. Wannerla Resser and Howell, B u l l . G e o l . Soc. Amer., v o l . 49, No. 2, (1938) p . 227. The f o l l o w i n g d i a g n o s i s i s based on Resser and Howell  ( I b i d ) and on p e r s o n a l o b s e r v a t i o n . E n t i r e t r i l o b l t e ovate, w i t h l a r g e ,  semicir-  c u l a r , h i g h l y convex, t h i n cephalon, which i s u s u a l l y s e v e r e l y f l a t t e n e d i n a d u l t specimens. expanded a n t e r i o r l y and t o u c h i n g r i m .  Glabella  strongly  D o r s a l furrow  deep on thorax but p o o r l y impressed on cephalon. G l a b e l l a r and o c c i p i t a l furrows s i m i l a r t o those o f  46. Olenellus. spine.  but s h a l l o w e r .  Rim wide,  O c c i p i t a l r i n g with short  i n c r e a s i n g r a p i d l y toward genal  angles.  G-enal spine s t r o n g , r a t h e r l o n g , t a p e r i n g r a p i d l y . P a l p e b r a l lobes short,  s h a r p l y bowed.  Hypostoma l a r g e , u s u a l l y l a t e r a l l y and p o s t e r i o r l y toothed, This plate  a t t a c h e d d i r e c t l y to e p i s t o m a l  i s wide, and toothed a l o n g i t s  E p i s t o m a l and marginal, p l a t e s l e n g t h of the former. the e p i s t o m a l p l a t e  a t t a c h e d throughout  regularly i n size,  furrows deeply Impressed.  the r e a r .  The f i f t e e n t h  D o r s a l and a x i a l axial  l o n g e r toward  lack  spines.  to f u l c r u m , w i t h wide p l e u r a l  furrows, which t a p e r g r a d u a l l y , the f u l c r u m .  seg-  segment has a v e r y s t r o n g a x i a l  s p i n e , but the two p o s t e r i o r segments Segments n e a r l y s t r a i g h t  1  except the  The f i r s t f o u r t e e n  spines, progressively  but  surface .  of seventeen  two, which are markedly s m a l l e r .  rings have.short  full  Both p l a t e s may be s t r i a t e d ^  Thorax i n the type s p e c i e s  last  i n n e r edge.  o f t e n shows a r e t i c u l a t e  ments, which decrease  plate.  P l e u r a l extensions  terminating bluntly  at  curve backward and t a p e r  t o sharp points;* Pygidium, a s m a l l , s l i g h t l y b l l o b a t e w i t h a median r i d g e , segments . 1  plate,  surrounded by t i p s of r e a r t h o r a c i c  47. Surface of e n t i r e t r i l o b l t e culate, scaly.  except m a r g i n a l p l a t e ,  coarsely  which i s s t r i a t e d or  • Wannerla i s d i s t i n g u i s h e d from a l l  other  o l e n e l l i d s by a unique combination o f f e a t u r e s : ding g l a b e l l a , 15th  reti-  normal t h i r d t h o r a c i c p l e u r a e ,  s p i n e , and c o a r s e l y r e t i c u l a t e Genotype: Rangej  expanlarge  surface.  O l e n e l l u s (Holmla) Wanner,. 1901  waloottanus.  Lower Cambrian o f North America and Greenland.  WANNERIA WALCOTTANA (WANNER) , Plate I I ,  Figs.  Olenellus  11-18.  (Holmla) waloottanus Wanner, Washington Acad:-Sci Pr No'.-3'(1901) p 267, p i . 31, F i g s . 1, 2 ; ; p i . 32, F i g s . 1-4.  Wanheria waloottanus Walcott ( p a r t ) , Smithsonian '" ™ V. . Misc.." C o l l . , v o l . 53, No. 6 (1910), p . 302, - p i . 30, F i g s . 1, 2, 5-12J p i . 31, F i g s . 12, 13; p i . 44, F i g . 6. Wanneria walcottana W a l c o t t , Smithsonian M i s c . C o l l . , v o l . 64, No. 3, (1916) p . 219, p i . 38, F i g s . 1, 2. Wanneria walcottana Resser and H o w e l l , B u l l . G e o l . Soc. Amer., v o l . 49, No. 2 (1938) p . 228, p i . 9, F i g s . 9, 10;; p i . 1 0 , . F i g s . 8-10; p i . 11. _ Diagnosis: One of the l a r g e s t 17 cm. i n w i d t h .  o f the o l e n e l l i d s , up to  Cephalon s t r o n g l y  convex.  Marginal  48. furrow deep'. spines.  Broad r i m , t e r m i n a t i n g i n l a r g e  G l a b e l l a t y p i c a l o f genus.  f r o n t a l lobe,  Strongly  genal convex  expanded to one t h i r d width o f  cephalon.  O c c i p i t a l lobe s l i g h t l y wider than p o s t e r i o r  glabellar  lobes,  r i s i n g s h a r p l y towards the r e a r .  may be p r e s e n t .  Dorsal, glabellar,  furrows s h a l l o w . h i g h l y convex,  P a l p e b r a l l o b e s deeply  erescentic,  s h o r t , and t a p e r i n g to t h e i r t e r m i n a -  as i n O l e n e l l u s .  Hypostoma l a r g e and  Thorax t y p i c a l of genus. t e r m i n a t i o n s marked w i t h f i n e ,  d o r s a l l y , as i n O l e n e l l u s . gently tapering troughs,  M a r g i n a l sutures denticulate.  Falcate  curved,  roughly t r a n s v e r s e v e n t r a l l y  a t the f u l c r u m .  spine  and o c c i p i t a l  t i o n o p p o s i t e the l a s t g l a b e l l a r l o b e .  striae,  Occipital  pleural  overlapping  and s u b - l o n g i t u d i n a l  P l e u r a l grooves  are wide,  t e r m i n a t i n g somewhat  bluntly  Segments p o s t e r i o r to the 15th,  pygidium, t y p i c a l of  and  genus.  Surface r e t i c u l a t e ,  the coarseness  of  p o l y g o n a l network v a r y i n g d i r e c t l y w i t h s i z e of not u s u a l l y v i s i b l e on those More than 100  the specimen,  s m a l l e r than' 25 mm. i n w i d t h .  specimens are p r e s e n t I n the  c o l l e c t i o n , r a n g i n g i n w i d t h from 2«5 mm. to 12 cm. young specimens the c o n v e x i t y  is striking.  In  During  growth the comparative w i d t h of the r i m appears t o  decrease.  49. Immature forms tend t o c u r l up; segments p o s t e r i o r t o the  1 2 t h are u s u a l l y c o n c e a l e d f o r t h i s r e a s o n . The a d u l t W. waloottana from Granbrook seem*  to d i f f e r from those i n the e a s t e r n p a r t o f the c o n t i n e n t In two d e t a i l s : hypostomae appear t o l a c k t e e t h , and s p i n e s a r e absent from the o c c i p i t a l r i n g and from t h o r a c i c segments a n t e r i o r t o the 15th. I f these apparent d i f f e r e n c e s are proven t o be r e a l , the c h o i c e w i l l have t o be made between r a i s i n g these specimens- t o s p e c i f i c rank, o r r e c o g n i z i n g t h a t d e n t i c u l a t i o n o f the hypostoma i s a f e a t u r e only of subspeclfic value i n c l a s s i f i c a t i o n . Order Superfamlly Family Genus  Op.isthoparida Corynexochoidae .Gorynexochidae Bohnia Waleott, 1916  Gorynexochus„.(Bonnla). Waleott, Smithsonian M i s c . . C o l l . , v o l . 64, No. 5 (1916) p. 325. Bonnia Raymond, Amer. J o u r . S c i . , 5 t h s e r . v o l . 15, No. 88 (1928) p . 309. Bonnla Resser, Smithsonian M i s c . C o l l . , v o l . 95, No. 4 (1936) p . 6. Bonnia Lochman, J o u r . P a l e o n t o l o g y , v o l . 21, No. 1 (1947) p. 68. "Granidium: If. P a l p e b r a l l o b e s medium s i z e , back of m i d l i n e o f g l a b e l l a b u t not q u i t e as f a r back as o n e - t h i r d .  50. 2 . G l a b e l l a either, p a r a l l e l - a i d e d or expanding slowly to a broad f r o n t ; regular, c o n v e x i t y ; f i r s t two p a i r s of g l a b e l l a r furrows, o f t e n o b s o l e t e , p o s t e r i o r p a i r sometimes w e l l d e f i n e d ; o c u l a r r i d g e obsolete In about o n e - h a l f .the species'. 3 . F i x e d cheeks approximately o n e - h a l f (may be a l i t t l e more) w i d t h o f glabella;. 4 . F i x e d cheeks h o r i z o n t a l or v e r y downsloping 5 . P o s t e r o l a t e r a l limbs s l i g h t l y l e n g t h of o c c i p i t a l r i n g ' .  sightly  less  than  6 . No f r o n t a l l i m b , a convex f r o n t a l border,, m a r g i n a l furrow a t s i d e s only. Pygidium: 1. N e a r l y s e m i c i r c u l a r i n o u t l i n e , 1, 2 or three p a i r s of a n t e r i o r m a r g i n a l spines. 2 . P l e u r a l l o b e s same w i d t h as a x i a l l o b e , a narrow m a r g i n a l furrow, a narrow but d i s t i n c t m a r g i n a l b o r d e r . 3* A x i a l lobe of medium w i d t h , - c y l i n d r i c a l i n shape, extending to b o r d e r , three c l e a r , one f a i n t segment and a t e r m i n a l portion." (Lochman,. 1947 p . 6 8 - 6 9 ) 1  Genotype: Range:  Bathyurus p a r v u l u s B i l l i n g s ,  Lower Cambrian, N o r t h America and A s i a  BONNIA c f COLUMBENSIS Plate  II,  1861  RESSER .  F i g s . 19, 2 0 .  Corynexochus (Bonnia) senectus Walcott ( p a r t ) , Smithsonian M i s c . C o l l . ; , v o l . 64,- No. .5 (1916) p . 3 1 9 , p i . 5 5 , F i g s . 7 - 7 c Bonnia columbensis R e s s e r Smithsonian M i s c . , C o l l . , v o l . 9 5 , No. 4 (1936) p . 9 f  51. Two p o o r l y p r e s e r v e d c r a n i d i a and  one  pygidium are p r e s e n t i n the c o l l e c t i o n , conforming t o generic d e s c r i p t i o n .  Tentative s p e c i f i c i d e n t i f i c a - ^  t i o n was made by r e f e r e n c e to the works c i t e d , l l y by comparing w i t h photographs by Waleott Apparently .this :was  especia-  (1916).  the form Waleott i d e n t i f i e d as  Prototypus seneetus ( S c h o f i e l d 1922, p . 1 2 ) .  52. .SELECTED BIBLIOGRAPHY  Beecher, C.E. (1897) O u t l i n e of a n a t u r a l c l a s s i f i c a t i o n o f t r i l o b l t e s ; Am. Jour...Sci., s e r . 4, v o l . 3, pp. 89-106, 181-207. B e l l , G.K. (1931) Disputed s t r u c t u r e s o f the Mesonacidae a n d . t h e i r . s i g n i f i c a n c e ; Am. Mus. N o v i t a t e s , no. 475, pp. 1-23. B u r l i n g , L.D. (1914) E a r l y Cambrian s t r a t i g r a p h y in.-the North .American, c o r d i l l e r a ; G e o l . Surv. Canada, Mus. B u l l , now-2, p p v 93-129. (1916) Paedeumias, and the Me sonacidae w i t h d e s c r i p t i o n of a-new s p e c i e s , h a v i n g a t . l e a s t 44 segments, from the Lower Cambrian o f B r i t i s h Columbia; Ottawa Nat.-,.vol. 30, no. 5, pp. 53-58. D e i s s , C. (1939) Cambrian f o r m a t i o n s of s o u t h western A l b e r t a and s o u t h e a s t e r n B r i t i s h Columbia; B u l l . G e o l . Soc. Amer., v o l . 50, pp. 951-1026. (1940) Lower and Middle Cambrian s t r a t i g r a p h y of southwestern and s o u t h e a s t e r n B r i t i s h Columbia; B u l l . G e o l . Soc. Amer., v o l . 51, pp. 731-794. Dunbar, C O . ti.sp.; 308.  Am.  (1925) Antennae i n O l e n e l l u s g e t z i . J o u r . S c i . , s e r . 5, v o l . 9, -pp. 303-  Evans, C.S. (1932) B r i s c o - D o g t o o t h Map-Area, B r i t i s h Columbia; G e o l . Surv. Canada, Sum. Rept., p t . A l l , pp. 160-175. Hall, J. " (1859) T r i l o b - i t e s o f the s h a l e s of .the Hudson R i v e r Group; Ann.. Rept. N.Y. S t a t e Cab. Nat. H i s t . v o l . 12, pp. 59-62. (1862) Supplementary note t o the ... t h i r t e e n t h , r e p o r t o f the r e g e n t s of the s t a t e c a b i n e t ; Ann. Rept. N.Y. State Cab. Nat. H i s t , v o l . 15, p . 114. Howell, B.F., e t a l . (1947) Terminology f o r d e s c r i b i n g Cambrian t r i l o b i t e s ; Journ. p a l e o n t o l V , v o l . 21, pp. 72-76. Keen, A.M. and M u l l e r , S.W. (1948) ..Stanford Univ. Press'.  Procedure i n Taxonomy;  53. Poulsen, C. (1927) The Cambrian, O z a r k i a n and Canadian faunas of.northwest Greenland; Medd. Gronland, v o l . 70, pp. 237-343. (1932) The Lower Cambrian'faunas o f . e a s t Greenland; Medd. Gronland, v o l . - 8 7 , no. 6, pp. 1-66. R a s e t t i , F. (1948) Lower Cambrian t r i l o b i t e s from the conglomerates of Quebec; J o u r n . P a l e o n t o l . , v o l . 22, pp. 1-24. . (1951) Middle Cambrian s t r a t i g r a p h y and faunas of_the Canadian Rocky Mountains; Smithsonian M i s c . C o l l . , v o l . 116, no. 5, PP« 1-270. Raw, F. -i (1925) The development o f L e p t o p l a s . t u s S a l t e r 1 and' o t h e r . t r i l o b i t e s ; G e o l . Soc. London,. Quart. Jour'., v o l . . 81, pp. 223--324. (1927) Ontogenies o f t r i l o b i t e s and t h e i r s i g n i f i c a n c e ; Am. J o u r . S c i . , v o l . 14, no. 78, pp. 7-35; no, 80,.pp. 131-149. . 1  (1936) Mesonacidae of Comley i n Shropshire, with a-dlscussion of c l a s s i f i c a t i o n w i t h i n the group; G e o l . Soc. London, Quart. Jour., v o l . - 9 2 , pp. 236-293. '  i  (1937) Systematic p o s i t i o n o f t h e O l e n e l l l d a e (Mesonacidae); J o u r n . P a l e o n t o l . , v o l . 11, no..7, pp. 575-597. Raymond,... P.E.-(1917)} Beecher's c l a s s i f i c a t i o n o f -- t r i l o b i t e s a f t e r twenty y e a r s ; Am. J o u r . S c i . , v o l . 43, pp. 196-210. . . (1928) Ontogenies of t r i l o b i t e s and t h e i r s i g n i f i c a n c e ; Am. J o u r . S c i . , s e r . 5., v o l . 15, pp. 168-170. (1920) The appendages, anatomy, and r e l a t i o n s h i p s . o f t r i l o b i t e s ; Mem. Conn. Acad. A r t s and S c i . , v o l . 7, 169 pp. Resser, C.E. (.1928) Cambrian f o s s i l s from the . . Mojave Desert; Smithsonian M i s c . C o l l . , v o l . . 81, no. 2, pp.. 1-14. (1936) Second c o n t r i b u t i o n t o nomenclature of t r i l o b i t e s ; . S m i t h s o n i a n M i s c . C o l l . , v o l . 95, no. 4, pp. 6-11.  54.  Resser, C.E. (1938) Cambrian System of the southern Appalachians; Geol. Soc. Amer'., spec, paper no. 15, 140 pp. Resser, C.E., and Howell, B.F. (1938) Lower Cambrian O l e n e l l u s zone of. the A p p a l a c h i a n s ; B u l l . G e o l . Soc. Amer., v o l . 49, pp". 195-248. R i c e , H.M.A. (1937) Cranbrook Map-Area, B r i t i s h Columbia; G e o l . Surv. Canada, Mem. 207. (1941) N e l s o n Map-Area, E a s t H a l f , B r i t i s h Columbia; G e o l . Surv. Canada, Mem. 228. Ross, R.J. (1948) R e v i s i o n s i n t h e , t e r m i n o l o g y of t r i l o b l t e s ; Am. J o u r . S c i . , v o l . 246, pp.  573-577.  S c h o f i e l d , S.J. (1915) Geology o f Granbrook MapArea, . B r i t i s h Columbia; G e o l . Surv. Canada, Mem. 76. (1922)^ R e l a t i o n s h i p , o f the, P r e Cambrian ( B e l t i a n ) t e r r a i n t o the. Lower Cambrian S t r a t a o f , s o u t h e a s t e r n B r i t i s h Columbia; G e o l . Surv. Canada, Mus. B u l l . no. 35* S t u b b l e f i e l d , C.J. (1936) C e p h a l i c sutures and t h e i r b e a r i n g on c u r r e n t c l a s s i f i c a t i o n s of t r i l o b l t e s ; B i o l . Rev., v o l . 11, pp. 1 - 3 0 . f  Swinnerton, H.Hv (1915) Suggestions f o r a r e v i s e d c l a s s i f i c a t i o n o f . t r i l o b l t e s ; G e o l . Mag. Londy,  v o l . 2, No . 11, pp. 487-497; No. 12, pp. 538. 545. ;  (1919) The f a c i a l suture of the t r l l o b i t e ; Geol.. Mag. Lond., v o l . 11, no> 3, pp. 103-110. Twenhofel, W.H., and Shrock, R.R. (1935) P a l e o n t o l o g y ; McGraw-Hill.  Invertebrate  Waleott, CD. (1886) Second c o n t r i b u t i o n t o the s t u d i e s on the Cambrian faunas of N o r t h America; U.S. G e o l . Surv. B u l l . 30, pp.. 1-369. (1891) The fauna of the Lower Cambrian o r O l e n e l l u s zone; U.S.-Geol. Surv., 10th Ann. Rept ., pp. .5H-658. 1  (1910) O l e n e l l u s and other genera of the Mesonacidae; Smithsonian M i s c . C o l l . , v o l . 53, No. 6, pp. 231-378.  55.  Walcott, C D . A(19l6) Cambrian t r i l o b i t e s ; Smithsonian Misc.._Coll., v o l , 64, no. 3>  pp.  157-258  B(1916) Cambrian t r i l o b i t e s ; Smithsonian. M i s c . . C o l l . , v o l . 64, no. 5,  pp. 503-456.  Walker, J.P. (1926) Geology and M i n e r a l D e p o s i t s of „.Windermere Map-Area, B.C., G e o l . Surv. Canada, Mem. 148. '• _ . Wanner, A. (1910) A new s p e c i e s of O l e n e l l u s from the Lower Cambrian of York County Pennsylvania; Wash. Acad. S c i . P r o c , v o l . 3 ,  pp.  267-272.  56.  PLATE I Olenellus eagerensls, ' Figs. 1 - 1 1 .  n . s p . and 0 . s c h o f i e l d l , n .  0 . ' eagere-nsis n . s p .  sp.  (p. 3 7 )  1* Specimen showing r e l a t i v e s i z e of thorax and base of 1 5 t h s p i n e . (Xl) Paratype. U . B . C , No.  2.  GT102.  Holotype (XI) showing o c c i p i t a l and a x i a l spines. U . B . C , No. G T 1 0 1 .  3» 5 , ' 6 , 7 , 8, 9 v (Xl) Cephala showing narrow r i m , c h a r a c t e r i s t i c g l a b e l l a , and r i d g e t o i n t e r g e n a l angle. Paratypes U . B . C , Nos. G T 1 0 3 , G T 1 0 5 GT109. (Note: 8 i s a p h o t o g r a p h . o f a p l a s t e r cast.) 4 . Incomplete specimen showing p o s t - o c u l a r mound » and c h a r a c t e r o f pleurae'. (X2.3) P a r a t y p e , U . B . C , No". GT104. . . 10.  Minute cephalon showing t y p i c a l p r o p o r t i o n s . ' (X5) Paratype. U . B . C , No;. G T 1 1 0 . . .  11.  Cephalon ( X 3 . 6 ) d o u b t f u l l y r e f e r r e d to t h i s s p e c i e s . _Note .expanded f r o n t a l lobev U . B . C ,  1  . No. GTlir.  F i g s . 12-17. 0 . schof i e l d l . !  12,  n . sp'« ( p . 40)  15, 16, 17, (X1.7, • l'.5> 2, 2.6 r e s p e c t i v e l y ) o h a r a c t e r i s t i c c e p h a l a , showing v e i n i n g , r e l a t i v e l y s t r a i g h t p o s t e r i o r margin and s h o r t palpebral lobesv Paratypes . U . E . C . , Nos . GT203 - GT206. 1  :  13'. Immature specimen p r e s e r v i n g i n t e r g e n a l and a x i a l spines. (X2.5) U . B . C . No> GT202. 14'. Holotype (X2.1) showing narrow r i m and a x i s , s t r o n g p o s t - o c u l a r node, s h o r t p a l p e b r a l l o b e , and v e i n i n g ' . U . B . C , No. GT20I.  PLATE I  57.  PLATE I I Paedeumias n e v a d e n s l s . O l e n e l l u s c f . g i l b e r t i Wannerla walcottana and Bonnia c f . columbensis Paedeumias nevadensls  (Waleott)  Figs.  1-5.  ( p . 44)  1. Two s m a l l complete specimens (X2.7) w i t h spine on 15th segment and s h o r t i n t e r g e n a l s p i n e s . U . B . C . , No. GT301. 2. Very s m a l l specimen (X4.7) w i t h a t l e a s t 10 t h o r a c i c segments. Note extremely s t r o n g i n t e r g e n a l s p i n e s , wide b r i m t r a v e r s e d by r i d g e and e n l a r g e d 3rd pleurae . U . B . C , No'. GT302. 1  3. E l o n g a t e d specimen (X4.1) w i t h l o n g 15th spine and 3rd pleuraef. Note wide r i m w i t h t r a c e o f narrow epistomal p l a t e , and i n t e r g e n a l spines* reduced d u r i n g growth. U . B . C . , No*. GT303. 5 . A d u l t cephala (XI) showing r e d u c t i o n i n w i d t h o f b r i m and. i n . development of i n t e r g e n a l spines. Nos. GT304, GT305'. r  Olenellus of.  g i l b e r t l Meek F i g s .  6-10  (p.  35)  F r o n t i s p i e c e . V e n t r a l c a s t of complete specimen (X4) showing a s y m m e t r i c a l - l i n e s p o s t e r o - l a t e r a l from e y e s , broken e p i s t o m a l p l a t e and s t r u c t u r e of 15th s p i n e . U . E . C . , No. GT351. 6, 7* Complete s h i e l d and cephalon showing narrow b r i m , a x i a l and o c c i p i t a l spines'. U.B.C, Nos. GT352, GT353. 8 ; Specimen w i t h b r o a d r i m and brim of i n t e r m e d i a t e width ( X I ) . U . B . C No. M i l . ( D o r s a l mold, photographed w i t h l i g h t from bottom r i g h t ) j  9 . Cephalon w i t h wider brim and narrower r i m than above^. U . B . C , No*. GT354. 10'. Wide-rimmed specimen showing s l i g h t Paedeumias type r i d g e on b r i m . Note marks i n t e r p r e t e d as t r a c e s o f antennules*. U . E ' . C , No'. GT355'* Wannerla walcottana  (Wanner) F i g s .  11-18  (p' . 47) :  l l . - 16'. Growth stages showing c o n v e x i t y and p r o p o r tions of cephala, strong o c c i p i t a l r i n g , character 1  PLATE I I  •58,  of r i m , and tendency o f s m a l l specimens to c u r l u p . Note mold of Paedeumias on 14.» U . B . C , Nos.  GT501 - GT506.  (Magnifications  2.7, 4 . 3 , 1 , r e s p e c t i v e l y . )  3, 1,  1,  1 7 * F l a t t e n e d d o r s a l i m p r e s s i o n (X0.8) w i t h a s s o c i a t e d hypostoma and e p i s t o m a l p l a t e . U . B . C , No. GT507. 18.Large hypostoma (XI) showing s t r i a t e d s u r f a c e and apparent l a c k o f d e n t i c u l a t i o r i . U . B . C , No. GT508. Bonnla c f columbensis Resser ( p . 50) 19, 20. Pygidium and c r a n i d i u m (X2.5) Nos. GT401, GT402.  U.B.C,  4  CANADA DEPARTMENT OF MINES A N D R E S O U R C E S HON T.A.CRERAR. MINISTER, CHARLES CAM SELL. DEPUTY MINISTER  80OO'  M I N E S 7000'  A N DG E O L O G Y  B R A N C H  JOHN McLEISH, DIRECTOR BUREAU  6 000'_  O FGEOLOGY A N D TOPOGRAPHY F.CC.LYNCH. CHIEF  5000'.  ISSUED 1938  4000'3000'-  V 2000 . IOOO'.  Sea-level  1 2  116°o o'  4945'-  L E G E N D  O  MODERN R E C E N T  A N D  P L E I S T O C E N E  N  o< z y o  o o o o  12  Glacial  drift.;  silt,  sand,  gravel.  C R E T A C E O U S OR T E R T I A R Y  OoO  </> z  Granodiorite  II  Li UJ  S o o o  CAMBRIAN L O W E R  C A M BRIAN  EAGER  IO  FORMATION:  argillite  N  CRANBROOK  FORMATION:  qu.artz.Ue,  magrvesite  <  UPPER  PURCELL  GATEWAY  SERIES  FORMATION':  dotoniitic  argillaceous  argillite.,  LOWER  quartxite,  concretiortary  PURCELL  and  pisolitic  dolomite  SERIES  PURCELL  EXTRUSWES:  andesitic  PURCELL  INTRUSIVES:  diorite  lava  sills  and  dyke*  z  <  SIYKH 5  and  DC  FORMATION:  highly  dclornitic  coloured  argillite  argillile  CO  <  KITCHENER  o  huff  UJ Ct CL  FORMATION:  weathering,  ('RESTON  arid  STEELE  fcxAJ.it Glacial  boundary (inclined.  (Ijocated,  purple,  white,  black.,  ui,,  quartxite, limy  banded, argillite,  argdlite  in  which  are tew or  approximate,  horixontal.  appro-innate.  white  quartxite,  areas  outcrops  weal?*/-*  quartxite.  tacking  assumed'  overturned)  u.s-.v timed)  stride  Geology  and  rusty  FORMATION: and  covered  (located,  vertical,  grey,  dolornitic  bedrock  Geological,  purple  argillaceous  argillite  grey-green,  Bedding  green,  FORMATION:  argillite  Drift,  and  quartxite  ALDRIDGE  FORT  grey argdlite  FORMATION  argillaceous  grey  green,  dolornitic.  — — . .'  by C.E.Cairnes.  1932; and  HMA.Ricc.193S.  49 30  Height Prospect  Contour Elevations izo"  125"  S  ,  I  1,,<I, I., JIHI  Ml/.:s  interval referred  IOO to Mean  feet sea-level  ; Surveyed  and reproduced  x  Mine  by tin- Hut-ran  in feet  5  dump  <>f flrulin/v  9  /  0  £ ^jl |  and  Topography.  

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