"Arts, Faculty of"@en . "Geography, Department of"@en . "DSpace"@en . "UBCV"@en . "Best, Raymond Victor"@en . "2012-03-06T20:14:15Z"@en . "1952"@en . "Master of Applied Science - MASc"@en . "University of British Columbia"@en . "Trilobites typical of the well known Olenellus zone of the Lower Cambrian constitute a large collection from the Eager Formation, near Cranbrook, B.C. Their classification is discussed and two new species described: Olenellus eagerensis n.sp. and Olenellus schofieldi n.sp.\r\nSince the use of certain structures in classifying olenellids has been disputed in the past, these and other less controversial features are critically examined, insofar as they apply to the genera and species present.\r\nFrom this study the writer assembles criteria which might be used by later workers to redefine the generic and specific positions of selected species of Olenellus and Paedeumias."@en . "https://circle.library.ubc.ca/rest/handle/2429/41178?expand=metadata"@en . "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. fii > /f 7 Members of the Department of GEOLOGY AND GEOGRAPHY THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1952 ABSTRACT T r i l o b i t e s t y p i c a l of the well known Olenellus zone of the Lower Cambrian constitute a large c o l l e c t i o n from the Eager Formation, near Cranbrook, B.C. Their c l a s s i f i c a t i o n i s discussed, and two new snecies described:: Olenellus eagerenals n.sp. and Olenellus s c h o f i e l d l r&spjV Since the use of c e r t a i n structures 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 disputed i n the past, these and other less controversial features are c r i t i c a l l y examined, insofar as they apply to the genera and species present. From th i s study the writer assembles c r i t e r i a which might be used by l a t e r workers to r e -define the generic and s p e c i f i c positions of selected species of Olenellus and Faedeumias^ TABLE OP CONTENTS ABSTRACT i INTRODUCTION \u00E2\u0080\u00A2 \u00E2\u0080\u0094 11 Acknowledgements \u00E2\u0080\u00A2 - - - i v Chapter I_ CRANBROOK AREA H i s t o r i c a l Summary \u00E2\u0080\u0094 \u00E2\u0080\u00A2 1 Strat igraphy \u00E2\u0080\u0094 \u00E2\u0080\u00A2 \u00E2\u0080\u0094 3 L i t h o l o g y of the O l e n e l l u s Zone r 4 Chapter I I TAXONOMIG.. CONSIDERATIONS -I n t r o d u c t i o n \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u00A2 6 Terminology \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u00A2 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 . . \u00E2\u0080\u0094 7 Terminal Segments \u00E2\u0080\u0094 \u00E2\u0080\u00A2\u00E2\u0080\u0094 7 F a c i a l Sutures \u00E2\u0080\u00A2 \u00E2\u0080\u0094 .-- 9 Cephalic Spines ; \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u0094 ;. \u00E2\u0080\u0094 12 F r o n t a l Lobe and Brim -\u00E2\u0080\u0094\u00E2\u0080\u0094 \u00E2\u0080\u00A2 : - \u00E2\u0080\u0094 13 Hypostoma and Epistomal P l a t e \u00E2\u0080\u0094 15 Thorax : - \u00E2\u0080\u0094 \u00E2\u0080\u0094 . \u00E2\u0080\u0094 \u00E2\u0080\u00A2 .17 Post-Ocular Nodes -\u00E2\u0080\u00A2- 19 Ornamentation \u00E2\u0080\u00A2 \u00E2\u0080\u0094 \u00E2\u0080\u0094 20 Growth Stages \u00E2\u0080\u00A2 \u00E2\u0080\u0094 \u00E2\u0080\u0094 \u00E2\u0080\u00A2 21 P r e s e r v a t i o n \u00E2\u0080\u0094 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2\u00E2\u0080\u00A2\u00E2\u0080\u0094 23 Cephalic and Thoracic R a t i o s \u00E2\u0080\u0094 \u00E2\u0080\u00A2 26 Systematic P o s i t i o n of O l e n e l l i d s = 27 Generic and S p e c i f i c D i s t i n c t i o n s --\u00E2\u0080\u0094 28 Recommendations f o r F u r t h e r Study \u00E2\u0080\u00A2 30 Chapter I I I DESCRIPTION OF GENERA AND SPECIES Q l e n e i l u s \u00E2\u0080\u0094\u00E2\u0080\u00A2 \u00E2\u0080\u0094 < \u00E2\u0080\u0094 \u00E2\u0080\u00A2 31 O l e n e l l u s .of., g i l b e r t ! 35 O l e n e l l u s ea^erenaIs. n . sp> \u00E2\u0080\u00A2-\u00E2\u0080\u00A2 37 -Olenellus. . .sohofieldl . n . s p . .\u00E2\u0080\u0094 \u00E2\u0080\u00A2\u00E2\u0080\u0094 40 \u00C2\u00AB Paedeumias \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 \u00E2\u0080\u00A2 42 Paedeumias nevadensis -\u00E2\u0080\u0094-\u00E2\u0080\u00A2\u00E2\u0080\u0094-\u00E2\u0080\u0094\u00E2\u0080\u00A2 44 Wanner i a T - : ? . 45 Wanner l a walcottana - r \u00E2\u0080\u0094 47 Bonnla ? \u00E2\u0080\u0094 .- 49 Bonnla e-f-. Qolumbensls 50 BIBLIOGRAPHY -EXPLANATION OF PLATES 52 56 ILLUSTRATIONS \u00E2\u0080\u0094 \u00E2\u0080\u00A2 Olenellus g l l b e r t l \u00E2\u0080\u0094 \u00E2\u0080\u00A2 Frontispiece Table I Cephalic and Thoracic Ratios 27 Table II Possible Generic D i s t i n c t i o n s 29 Plate I Olenellus eagerensis ri\u00C2\u00BB sp\u00C2\u00AB and Olenellus s c h o f i e l d i . n. sp> - Facing Page \u00E2\u0080\u0094 56 Plate II Paedeumias nevadensls. Olenellus of. g i l b e r t i . Wanneria walcottana and Bonnla c f . columbensis\". Facing Page 57 l i . A LOWER CAMBRIAN TRILOBITE FAUNA \"FROM NEAR. CRANBROOK,'B.C.*. INTRODUCTION The f o l l o w i n g study i s based upon a c o l l e c t i o n of t r i l o b i t e s , made l a r g e l y by Mr. C. G a r r e t t , 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. The c o l l e c t i o n was taken from two l o c a l i t i e s of d i f f e r i n g l i t h o -logy w i t h i n the Eager Formation. I t c o n s i s t s 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 of the w e l l known O l e n e l l u s zone, which define the age of the rocks i n which they were found as Lower Cambrian. I t may be that conclusions based on observations of fauna from a s i n g l e l o c a l i t y should be r e s t r i c t e d to that p a r t i c u l a r a r e a . A student faced w i t h . o n l y one phase of a l a r g e r problem may be-tempted to extrapolate unreasonably. Many g e n e r a l i z a t i o n s can be quoted from the l i t e r a t u r e analogous to those of the three b l i n d men d e s c r i b i n g an elephant. But i n the wider f i e l d of p a l e o n t o l o g i -c a l r e s e a r c h a clue to one of 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 , p r o v i d i n g confirma-t i o n of a t e n t a t i v e hypothesis or the r e f u t a t i o n of an accepted p r i n c i p l e . i l l 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 c o l l e c t i o n . I t i s almost c e r t a i n that only a few of the l e g i t i m a t e species have been r e c o g n i z e d . A great d e a l more could be learned of the ontogenies, and p o s s i b l y of s p e c i f i c and generic 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 p a l a e o n t o l o g i s t s conversant w i t h the outstanding problems would provide much v a l u a b l e information 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 view. 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 that the observations made here w i l l be of some value 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 i t : ACKNOWLEDGEMENTS The w r i t e r g r a t e f u l l y acknowledges the guidance and c o n s t r u c t i v e c r i t i c i s m of Dr. 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 t h i s t h e s i s , and Invaluable a s s i s t a n c e i n photograph-i n g specimens. To Dr. M.Y\u00C2\u00AB Will iams 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 Mining and Metal lurgy k i n d l y encouraged and a s s i s t e d i n experimental attempts at micro-photography. 1. CHAPTER I CRANBROOK AREA H i s t o r i c a l Summary The f i r s t extensive g e o l o g i c a l 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, 1922). P r i o r to h i s 1915 memoir b r i e f reconnaissances had been made by Dawson (1895) and McEvoy (1899). The most recent r e v i s i o n of s t r a t i g r a p h y near Granbrook was com-p l e t e d by Rice (1937, 1941) a copy of whose 1937 map Is i n c l u d e d i n the present paper. The presence of the O l e n e l l u s zone was f i r s t r e p o r t e d between Granbrook and Port Steele by S c h o f i e l d (1922). The f o s s i l s he c o l l e c t e d were sent to C D . Waleott, who I d e n t i f i e d the f o l l o w i n g t r i l o b i t e s : G a l l a v l a o f . nevadensis Waleott Wannerla n . sp ? Mesonaois g i l b e r t i Meek Wannerla o f . waloottanus (Wanner) O l e n e l l u s c f . fremontl Waleott Prototypus seneotus B i l l i n g s Waleott i s quoted concerning t h i s c o l l e c t i o n as s a y i n g : \"This fauna belongs to the upper p a r t of the Lower Cambrian and i t i s e s s e n t i a l l y the same as that found above the tunnel at Mt. Stephen, B . C . , and i s a l s o 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 or l e s s a l l along the c o r d i l l e r a n system down into southern Nevada.\" (Ibid, p 12) The species found by Rice (1937) apparently did not d i f f e r to any great extent, since no further faunal information i s embodied i n hi s report. Although professional geologists were mainly interested i n the Cranbrook.Area.from an economic point of view, at le a s t two amateurs became very keen f o s s i l hunters. Col. Pullen and C. Garrett made exten-sive 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 Steele road, the second just east of St. Eugene Mission. In this, second l o c a l i t y they put i n a small a d i t i n grey shale and were rewarded.by obtaining a very f i n e c o l l e c t i o n , including\u00E2\u0080\u00A2numerous examples of the young growth-stages of Olenellus, Paedeumias and Wanneria. Unfortunately, c e r t a i n l o c a l inhabitants, suspecting that such incomprehensible actions were con-nected with something more remunerative than a \" t r i l o -b i t e mine\", staked out claims. C o l l e c t i n g had to be\" d i s -continued and the adit f i l l e d i n . Dr. M.Y. Williams of the University of B r i t i s h Columbia made a f a i r l y extensive c o l l e c t i o n from both l o c a l i t i e s i n 1954, The Garrett c o l l e c t i o n , obtained l a t e r by the University, together with that of Dr. Williams, t o t a l s some fourteen hundred specimens, and furnishes the material for t h i s study. STRATIGRAPHY The presence of Bonnla and Olenellus i n the Eager Formation places the age of these rocks i n the upper part of the Lower Cambrian (Rasetti, 1951)\u00E2\u0080\u00A2 The Eager a r g i l l i t e s , some thousands of feet thick, are underlain by the Granbrook Formation, which Is 600 feet thick. The contact between these two i s believed by Rice (1941) to be gradational. The Cranbrook Formation consists largely of quartzite, pebble conglomerate, and some magnesite; although f o s s i l s are absent, i t s age i s also assigned to the Lower Cambrian. The Cranbrook rests uneonformably on Proterozoic rocks of Upper P u r c e l l Age. The age relationships of the Lower Cambrian Olenellus zone have recently been studied by Rasetti (1951)\u00E2\u0080\u00A2 Tentatively the Eager Formation may be cor-related with Peyto limestone, that i s , the top of the Lower Cambrian St. Piran sandstone at Kicking Horse Pass. I t i s also correlated with the lower part of the Burton Formation at Elko (Schofield, 1922). 4 LITHOLOGY OF THE OLENELLUS ZONE I t i s stated by Resser and Howell (1938, p. 207) 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 parts of the world i s astonishing, 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 shales bearing o l e n e l l i d t r i l o b i t e s . For ... , the most part, these rocks are clay shales, i n .r many places calcareous, but everywhere f i n e grained; the Joint surfaces are almost u n i v e r s a l l y stained with limonite generally 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 calcareous content i n the o r i g i n a l muds to prevent many tests from being completely fl a t t e n e d . \" The Eager Formation i s no exception to t h i s statement. According to Rice (1937, p. 21) \"The bulk of the formation consists of dark grey, often rusty-weathering a r g i l l i t e ... Blue-grey, o l i v e green, and. reddish platy a r g l l l i t e s also occur i n places. They are a l l soft, e a s i l y deformed rocks and are everywhere f o l i a t e d . The formation i s not generally limy, but beds' of calcareous a r g i l l i t e may occur i n any part of i t ...\" It i s apparent from the foregoing statements that the Olenellus 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 within the zone i t s e l f , i n t h i s case the Eager Formation, c e r t a i n p e c u l i a r i t i e s of faunal d i s t r i b u t i o n are 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 o c a -l i t i e s named here A and B. At l o c a l i t y A# \u00C2\u00B0*i t l i e main Cranbrook-Fort Steele road (see map i n back cover) the rocks are sof t l i m o n l t i c a r g l l l i t e s ; at B, just south 5. of St. Mary River and east of St. Eugene Mission, they consist of harder, dark grey, rusty-weathering, dolomitic, 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 Olenellus ef . g i l b e r t l and Paedeumias nevadensls; but at B, not only Is the proportion of 0. eagerensls higher, but here were found the only spec imens r e f e r r e d to 0. s c h o f i e l d l and to Bonnia c f . columbensls'. Since the writer d i d not carry out the c o l -l e c t i n g himself, numbers of imperfect or incomplete specimens may have been abandoned, with consequent \"weighting\" of the proportions of species c o l l e c t e d . Furthermore, the stratigraphic r e l a t i o n s h i p of the two outcrops i s not known,, so that i t i s possible that e n t i r e l y d i f f e r e n t ages within the Olenellus zone are represented\". Although no p o s i t i v e conclusion may be drawn from these observations of faunal d i s t r i b u t i o n , the f a c t s do not, at least, contradict the suggestion made by Rasetti (1951, P 82)s \"The Olenellus zone may represent a shaly f a d e s of the Lower Cambrian deposits rather 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, olenellids.seem to p r e v a i l when the Lower Cambrian i s represented by s i l i c i o u s . s h a l e s , while Bonnla and small ptychoparid t r i l o b i t e s are dominant i n limestone or dolomitic formations, regardless of age.'1 _ CHAPTER I I TAXONOMIC CONSIDERATIONS I n t r o d u c t i o n Probably no group of t r i l o b i t e s has aroused more controversy and d i s c u s s i o n than the o l e n e l l i d s . They are unique i n many ways. But f o r years t h e i r p e c u l i a r i t y was not recognized, and the greatest e f f o r t s were made to f i t them i n t o e s t a b l i s h e d schemes of c l a s s i f i c a t i o n , . 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 considered to be neces-s a r i l y on the d i r e c t l i n e of descent. Homologizlng of p a r t s was s t i l l a new idea i n the l a s t century, of great s c i e n t i f i c v a l u e , but c a r r i e d to extremes-. Some traces of these abuses have l i n g e r e d on to the present day. The controversy a r i s i n g i n the study of o l e n e l l i d s was concerned mainly with the development and o r i g i n of two or three features of the carapace: t e r m i n a l segments, c e p h a l i c sutures, and to a l e s s e r extent, c e p h a l i c s p i n e s . Since an attempt i s made i n t h i s paper to 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 , the above features and some others of a l e s s c o n t r o v e r s i a l nature are discussed i n s o f a r as they apply to the genera and 7. species examined. Furthermore, although 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 that at some future time enough data 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. With t h i s i n 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 c r i t e r i a f o r a r e d e f i n i t i o n of \"Mesonacls\" ( B . B . ) ' . TERMINOLOGY The terminology used throughout t h i s paper i s e s s e n t i a l l y that of Howell et a l * (1947) with some of the modif icat ions suggested by Ross (1948) and adopted by R a s e t t i (1951)\u00E2\u0080\u00A2 Since i t i s suggested that the a n t e r i o r of the cephalon of o l e n e l l i d s i s not separable i n t o f i x e d and free cheeks, the \"brim\" Is r e s t r i c t e d i n t h i s paper to mean that p a r t of the c e p h a l i c surface at the c e n t r e , l y i n g between the f r o n t a l lobe and the r i m * To avoid tedious 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 to as \"the 1 5 t h s p i n e \" , even when other spines are not present on segments a n t e r i o r t o the 1 5 t h * TERMINAL SEGMENTS The rudimentary p o s t e r i o r segments of o l e n e l l i d s are only r a r e l y observed. Under c o n d i t i o n s of 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, o r perhaps - f o l d e d forward under the t h o r a x . In most specimens, since these segments were probably very f r a g i l e , they seem to have been l o s t e n t i r e l y . For many years G.D. Walcott was an i n f l u e n -t i a l proponent of the theory that the 15th spine on O l e n e l l u s was a t e l s o n , l i k e that on Limulus, the modem k i n g c r a b . The presence of t e r m i n a l segments and small p y g i d i a i n a l l other o l e n e l l i d genera decided him to set up Mesonaols r a t h e r than O l e n e l l u s as the type-genus of the family Mesonacldaev The genotype, M. vermontana. was known to possess ten rudimentary segments, and a small pygidium, p o s t e r i o r to the s p i n e -b e a r i n g 15th t h o r a c i c 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 species of O l e n e l l u s were found to possess rudimentary segments, n e c e s s i t a t i n g 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 nearest r e l a t e d genera known to possess such f e a t u r e s . Resser (1928) a f t e r showing c o n c l u s i v e l y that O l e n e l l u s d i d Indeed possess rudimentary segments, pointed out that d i f f e r e n c e s i n these could be detected 9. at the generic l e v e l ; those, of Mesonacls had d e f i n i t e , grooved pleurae, those of Olenellus had ungrooved pleurae, out those of Paedeumias lacked pleurae altogether. In 1938, Resser and Howell, i n r e v i s i n g the genus Olenellus established the f a c t that i t s posterior segments did not necessarily possess pleurae. Generic redescription included c e r t a i n other c h a r a c t e r i s t i c s , so as to Include forms formerly named Mesonacls. Thus, the names Mesonacls and Mesonacidae were dropped. Observations With the exception of Wannerla walcottana. -the specimens i n the c o l l e c t i o n , although well preserved, generally exhibit neither the posterior rudimentary segments nor the. pygidlum. In nearly every complete thorax of Olenellus and Paedeumias the 1 5 t h spine i s extremely heavy, i t s base extending f u l l y across the a x i a l lobe, and tapering f a i r l y slowly, so that i t e f f e c t i v e l y conceals whatever l i e s beneath. One speci-men of Olenellus c f . a l l b e r t i has no les s than three very poorly preserved segments posterior to the spine-bearing 1 5 t h , but no pygidium has been observed. FACIAL SUTURES The c l a s s i f i c a t i o n of 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, or l i n e of Junction of the f i x e d and f r e e cheeks of the cephalon. I t i s g e n e r a l l y assumed that t h i s was.the l i n e along which the t r i l o b i t e cephalon s p l i t during e c d y s i s , the p e r i o d i c moulting common to a l l Crustacea. I t i s p o s s i b l e that the sutures of t r i l o b i t e s are not i n v a r i a b l y homologous. According t o S t u b b l e f i e l d (1936, p 410): \"It cannot be denied t h a t the presence of cephalic sutures f a c i l i t a t e d e c d y s i s , but i t i s at l e a s t arguable that the sutures e x i s t e d only f o r t h i s purpose.?' The o l e n e l l i d s have long been a source of d i f f i c u l t y i n taxonomy, since they do not appear to possess these u s e f u l s t r u c t u r e s i n f u n c t i o n a l form, I . e . as a means of f a c i l i t a t i n g ecdysisv Observa-t i o n s , made of specimens since the f i r s t d e s c r i p t i o n of O l e n e l l u s ( H a l l , 1859) have been v a r i o u s l y i n t e r -p r e t e d . A complete h i s t o r y of the disputes over the f a c i a l sutures i n o l e n e l l i d s i s g iven by Raw (1937) and S t u b b l e f i e l d (1936). B r i e f l y , the main opinions concerning f a c i a l sutures and t h e i r s i g n i f i c a n c e may be summarized: r. Rudimentary - i n process of o r i g i n or s y n t h e s i s . ( I b i d ) . 2. V e s t i g i a l - or i n a c o n d i t i o n of symphysis. (Raw, 1937). 11. Observations In examining nearly 500 complete cephala of Olenellus and Paedeumias.the writer has made a number of observations: 1. The tendency f o r the cephalon to break i n c e r t a i n places i s indisputable. The l i n e s of ant e r o - l a t e r a l fracture, interpreted by B e l l (1931) and others 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 are seldom symmetrically developed. (b) Ho two cephala have been found with the fractures i d e n t i c a l . (c) They are no more frequent i n occurrence than the lo n g i t u d i n a l l i n e of fracture down the approximate centre of the g l a b e l l a . (d) Unbroken cephala show no l i n e , r a i s e d or depressed, suggestive of an inherited 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, therefore, that these fractures are e n t i r e l y mechanical i n o r i g i n , (see Preservation) 2. The pos t e r o - l a t e r a l r a i s e d l i n e running from under the eye toward the genal angle i s as often as not asymmetrically developed. Fre-quently, t h i s l i n e separates into two or more branches indistinguishable from the venation referre d to by Lockman (1947, p. 61). Fracture p r a c t i c a l l y never occurs along or p a r a l l e l to t h i s l i n e . I t appears that 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 significance i t i s not part of a v e s t i g i a l f a c i a l suture, nor, i n i t s present form, does i t appear to be a rudimentary suture i n the process of o r i g i n . 3\u00C2\u00BB The intra-marginal sutures described by Resser (1928) i n Olenellus fremonti are c l e a r l y exhi-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 Olenellus and Paedeumias, but 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 these, the genal spines are r e t a i n e d as a prominent feature i n a d u l t s of a l l genera; the i n t e r g e n a l spines are often l o s t during development; the a n t e r o - l a t e r a l s p i n e s , with the one exception of O l e n e l l o i d e s a r e . i f 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\u00C2\u00BB 579) that the c e p h a l i c spines i n o l e n e l l i d s are segmental i n o r i g i n . As S t u b b l e f i e l d p o i n t s out (1936, p. 425) there seems to 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. 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 not, 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 that the r e t e n t i o n of cephalic spines Is a p r i m i t i v e c h a r a c t e r i s t i c . But whatever t h e i r f u n c t i o n , i f any (Raymond 1928, p. 168) they are taxonomically u s e f u l * Observations No a n t e r o - l a t e r a l spines such as described 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. In the c o l l e c t i o n , down to the smallest cephalon, 1.25 mm In width, 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 than 5 mm. wide of 0'. c f g i l b e r t ! and P. nevadensis, 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 spines In these species 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 . In almost a l l specimens possessing 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 across the cheek-to-the r e a r of the p o s t - o c u l a r node,, opposite the o c c i p i t a l furrow. 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 i s u s u a l l y d i s t i n c t l y developed. I t s distance from the r i m , i t s s i z e r e l a t i v e both to the succeeding lobes and to the whole cephalon, and i t s convexity, have a l l been used as a i d s i n c l a s s i f i c a t i o n . The r e l a t i v e s i z e of the a n t e r i o r lobe to a large extent governs the shape and taper of the g l a b e l l a ' . The s e p a r a t i o n of r i m from g l a b e l l a by a brim possessing an a x i a l r i d g e i s d i a g -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 to \" . . . c o m p r e s s i o n of the t e s t onto the hypostoma s t a l k during f o s s i l i z a t i o n . \" (Resser and Howell 1938 p . 225) 14. Convexity i s i t s e l f a r e l a t i v e quantity, most e a s i l y estimated i n terms of the abruptness of the r i s e of the anterior lobe from i t s own f r o n t a l margin. Observations One of the most s t r i k i n g features of the cephalon of Olenelliis eap;erensis at a l l growth stages examined i s the extremely abrupt r i s e of the f r o n t a l lobe from the narrow rim. The f r o n t a l lobe of 0. c f . g i l b e r t i i s pre-ceded by a brim and rim of approximately equal width. Between 0. cf. 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, with the width of the brim varying from one to three times that of the rim. The rim 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 for i t s broad rim (Pi.IE P i g . 8 ) \u00E2\u0080\u00A2 The growth stages of 0. c f . g i l b e r t ! and P. nevadensis le s s than 8-10 mm. i n width are i n d i s t i n -guishable; the brim i s wide i n a l l cephala examined, and i n the better preserved specimens possesses the t y p i c a l Paedeumias ridge. Consequently, a l l minute forms of these two species are together referr e d to \"Paedeumias\" i n t h i s paper. 15: HYPOSTOMA AND EPISTOMAL PLATE The hypostoma, I f w e l l preserved, may be a valuable a i d i n I d e n t i f i c a t i o n of o l e n e l l i d s : . As i n most t r i l o b i t e s , i t i s a l i p - l i k e s t r u c t u r e f i t t i n g convex down beneath the a n t e r i o r - g l a b e l l a r lobe;. The hypostomae of Wannerla and Paedeumias from the type l o c a l i t i e s are equipped with d e n t i c u l a t e p o s t e r i o r margins; i t i s b e l i e v e d (Waleott, 1910, p . 328) that O l e n e l l u s g i l b e r t l possessed the same feature 1 * In O l e n e l l u s and Paedeumias the hypostoma i s attached to the epistomal p l a t e , which i s i n t u r n apparently connected a n t e r i o r l y to the doublure, the two together occupying the width of the r i m at the axis'. The most important diagnostic feature of Paedeumias i s t h e \" s t a l k e d attachment of the hypostoma to the epistomal p l a t e , often 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 across the b r i m . I f the epistomal 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 ince the two must be attached, three condit ions can govern the mechanics of attachment. I f the r i m Is adjacent to the f r o n t a l lobe the hypostoma and epistomal p l a t e may be attached d i r e c t l y ; I f the distance between f r o n t a l lobe and rim. i s i n c r e a s e d , / 16. e i t h e r the p l a t e and rim 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 develop. Concerning Paedeumias, Resser and Howell (1938, p . 226) s t a t e : \"The hypostoma i s attached to the m a r g i n a l , or more l i k e l y , epistomal p l a t e , by a s t a l k whose l e n g t h equals the distance from the g l a b e l l a to the r i m . \" Observations The epistomal p l a t e s of 0. eagerensls and 0. s c h o f i e l d l have not been observed w i t h any c e r t a i n t y . That of w. waleottana i s s l i g h t l y narrower than the r i m , with hypostoma i n d i r e c t connection. D e n t i c u l a t i o n has been observed on only one hypostoma a s s o c i a t e d with a s m a l l Paedeumias. 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 tana, although the epistomal p l a t e of t h i s t r i l o b i t e i s as prominently d e n t i c u l a t e as that of the h o l o t y p e . Two very p e r f e c t s h i e l d s of O l e n e l l u s of g i l b e r t ! , although l a c k i n g the hypostoma, r e t a i n the epistomal p l a t e s l i g h t l y drawn back from the r i m . H a l f -way from the genal angle to the centre the p l a t e i s about h a l f the width of the r i m , widening to one r i m -width at the a x i s . . At t h i s p o i n t a narrow s e c t i o n of the p l a t e i s missing (see F r o n t i s p i e c e ) . The brim here i s about twice the width of the r i m . On a second specimen I T . the. p l a t e Is unbroken, and a widened p o r t i o n at the a x i s i s s l i g h t l y longer than the missing p a r t i n the f i r s t . 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 the widened or missing p a r t represents the attachment of the hypostoma, such attachment must have been narrower than l o n g , i n other words a s t a l k . This inference cannot be confirmed at present,^ since no s t a l k has been d i r e c t l y observed?. The epistomal p l a t e of o l e n e l l i d s seems to have been hooked or anchored i n some way at 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 to the observed drawing back of the p l a t e 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 In most o l e n e l l i d s the a x i a l spine of the 15th t h o r a c i c segment i s very large'. But the o v e r a l l aspect 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 t h i r d p l e u r a l segments, extending i n t o s lender spines 1 . The shape of the thorax, ' \"wide\" or \"narrow\" of authors, i s compounded of s e v e r a l v a r i a b l e s : width of 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 both to each 13 other and to t h e i r length, and to 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 to b u r i a l . The main, central parts of the carapace were r i g i d and more or less 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 that the f a l c a t e t i p s of the pleurae were less so. Consequently, the degree of flexure of these t i p s , either before 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 value. But the sharp or gradual angling back of pleurae at a point proximal from the outer t i p of the p l e u r a l groove may frequently a i d In dist i n g u i s h i n g specimens. For instance, the pleurae of Q\u00C2\u00AB eagerensis usually angle back sharply, whereas those of Paedeumias and most species of Olenellus tend to swing back more gradually. In some species the r e l a t i v e length of p l e u r a l groove to f a l c a t e t i p reduces uniformly from front to back, as i n W. waleottana (Wanner, 1901, p. 267). In t h i s species, where the t i p s are not unduly extended into spines, 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 pleuron might have come, permitting a rough estimate to be made of the size of o r i g i n a l s h i e l d . But the r e l a t i v e length of a selected p l e u r a l groove may also be compared between species as a i 9 ; d i a g n o s t i c a i d . I f the second p l e u r o n , which i s f r e -quently preserved and e a s i l y i d e n t i f i a b l e , i s examined, the r a t i o of l e n g t h of p l e u r a l groove to width of a x i a l lobe i s reasonably constant f o r a p a r t i c u l a r s p e c i e s , \u00E2\u0080\u00A2This r a t i o i s i n the order of 5:4 i n Paedeumias and i n most species of O l e n e l l u s , but only about 3:4 i n 0'. 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 been b r i e f l y r e f e r r e d to by a number of authors,, They are smooth mounds, u s u a l l y e l l i p t i c a l , \" . . . o n the f i x e d cheeks back o f , and i n s i d e o f , the eyes\" (Resser and Howell , 1938, pm 225) :\u00C2\u00AB On O l e n e l l u s and Paedeumias they seem to be best developed i n those species whose p a l p e b r a l lobes are some distance from the p o s t e r i o r c e p h a l i c 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, evenly s l o p i n g up and back from the Junction of the d o r s a l and p a l p e b r a l furrows to maximum e l e v a t i o n opposite the r e a r of the 3 r d g l a b e l l a r lobe|. At t h i s p o i n t they drop away s t e e p l y to disappear opposite the o c c i p i t a l furrow. 0 . eagerensis , on the other hand, possesses long 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 along the s ide 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 research, no function may d e f i n i t e l y be assigned to post-ocular nodes or mounds. But i t seems reasonable to assume that they have some anatomical explanation. As a f i r s t working hypothesis i t i s suggested that they represent the ven t r a l \"housing\" f o r paired organs, possibly ovaries, perhaps digestive glands, or both. I f they are ultimately proven to r e f l e c t i n t e r n a l anatomy they may well be of greater taxonomic value than has hitherto been thought. ORNAMENTATION Surface ornamentation i s not 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 , but c e r t a i n species may exhibit unique markings which are diagnostic'. Thus, by means of the r e t i c u l a t e surface ornamentation \"even a small fragment can be assigned to Wannerla\" (Resser and Howell, 1938, p. 246). This type of polygonal pattern has been observed on the dorsal surface of a l l the larger specimens of W. walcottana i n the c o l l e c t i o n . The cheek surface of Olenellus s c h o f l e l d l i s unlike that of any other form i n the c o l l e c t i o n , but 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 inoscula-t i n g , raised l i n e s , reminiscent of the v e i n pattern of a l e a f . According to Lochman (1947, p\u00C2\u00AB 61) t h i s venation i s neither ornamentation nor diagnostic; 21 \"... but rather i t appears to be the Impress of an i n t e r n a l anatomical structure on the carapace. As i t has been observed i n many apparently unrelated genera ranging through the Paleozoic, It i s considered to be a feature 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 that figured by Waleott (1910) on 0. g i l b e r t l has not been observed on any specimens here. However one incomplete cephalon of 0 :. ef... g i l b e r t l exhibits 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 kind. Although the writer thinks that t h i s has an inorganic explanation, that 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 have been determined by the d i f f e r e n t i a l chemical influence of an o r i g i n a l surface ornamentation. The pattern of overlapping l i n e s on the t i p s of pleurae of Olenellus h a l l l (Waleott) figured by Waleott (1910, p i . 31, f i g s . 10, 11) show them to be roughly transverse on the ventral surface but sub-longitudinal on the d o r s a l . This rule appears to apply to a l l the species of Wannerla, Olenellus and Paedeumias i n the Garrett c o l l e c t i o n . GROWTH STAGES One of the most important phases of palaeon-t o l o g i c a l research, a f t e r the purely descriptive work has been done, i s the analysis of observations. Relation-22 ships between groups are sought, and e f f o r t s made to disentangle evolutionary trends. The greatest use, both economic-and purely s c i e n t i f i c , can be made of informa-t i o n only when i t s l i m i t a t i o n s are known. The study of perhaps greatest taxonomic value i n paleozoology i s that of growth stages, f o r one of the most widely accepted-principles has been the biogenetic law; \"Ontogeny recapitulates Phylogeny\". The growth stages of only a few o l e n e l l i d s have been studied (Walcott, 1910). But the extent to which theories of evolution have been developed from such studies i s best i l l u s t r a t e d by reference to Raw (1925, 1927, 1936, 1937). But such theories should be accepted with some caution. I t i s possible that a t r i l o b i t e d i d not s t a r t to secrete hard parts 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 to provide only doubtful clues as to i t s r e l a t i o n s h i p s . Furthermore, some of the ontogenies des-cribed i n the past may have been based on i n s u f f i c i e n t specimens. Enough material i s present i n t h i s c o l l e c t i o n to warrant further work, but the writer regrets the lack of time to complete i t himself. An intensive 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 c o l l e c t i o n , w i t h a view to confirming 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 ( 1 9 1 0 ) i n s o f a r as they apply to the fauna of the Eager Formation. PRESERVATION The O l e n e l l u s fauna i s n e a r l y always compara-t i v e l y w e l l preserved. Apart from the crushing of very t h i n , convex t e s t s , which i s to be expected even under the best c o n d i t i o n s , the f i n e sediments tend to preserve extremely f r a g i l e types of Crustacea such as the homopods Tuzola and Anomalooarls, and to favor the r e t e n t i o n of considerable d e t a i l i n the o l e n e l l i d s them-s e l v e s . The degree of p r e s e r v a t i o n has a very r e a l b e a r i n g on taxonomy. Removal of d i a g n o s t i c d e t a i l s , d i s t o r t i o n of s t r u c t u r e s , and even the superimposit ion of secondary c h a r a c t e r i s t i c s of inorganic 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 -f i c a t i o n d i f f i c u l t . In the m a t e r i a l s t u d i e d here, a t t e n t i o n has been drawn to the almost complete absence of p y g l d i a . In t h i s connection, i t i s r e g r e t t a b l e that the t h o r a c i c segments of 0 . eagerensis are seldom preserved behind the 4 t h or 5 t h , and no p l e u r a l segments of Bonnla have been found at a l l . I t may be that the apparent absence 24. of i n t e r g e n a l spines i n l a r g e r specimens of Paedeumias i s a matter of incomplete p r e s e r v a t i o n . The extent of d i s t o r t i o n i n specimens i s often very d i f f i c u l t to estimate. I t i s reasonable, to assume that v a r i a t i o n s from a common \"mean shape\" e x i s t e d i n every c o n s p e c i f i c t r l l o b i t e p o p u l a t i o n . I f only one recognizable species were present , the v a r i a -t i o n s around the mean would fol low a normal d i s t r i b u -t i o n curve, with only one maximum p o i n t . However, i n the course of b u r i a l , compaction and s u b j e c t i o n to shearing s t r e s s e s , o r i g i n a l l y I d e n t i c a l forms might conceivably y i e l d i n a d e f i n i t e number of ways, l i m i t e d perhaps by the type of basic s t r u c t u r e . This c o u l d 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 \"types\". I t i s p o s s i b l e that some of the recognized species of t r i l o b l t e s owe t h e i r s p e c i f i c stature to such a combina-t i o n of mainly inorganic circumstances. The convex c e p h a l i c s h i e l d of an o l e n e l l i d i n course of f l a t t e n i n g , because i t i s wider than l o n g , may y i e l d more e a s i l y along the a x i s than l a t e r a l l y . Cracks are most l i k e l y to develop where greatest t e n s i o n i s e f f e c t i v e . Such a p o i n t appears to e x i s t at the f r o n t a l margin at the c e n t r e . Subsequently, the crack 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 of maximum convexity, that Is, along the g l a b e l l a . Once the two halves were independent the next point of maximum tension would appear to l i e at or near the base of the palpebral lobe. In t h i s way i t i s possible to account f o r the commonly observed cephalic cracks: the primary fracture occurring along the axis, the secondary p a i r f o r t u i t o u s l y simula-t i n g the anterior branch of the f a c i a l suture. Compression acting i n the s o l i d rock may be quite intense, and i t s manifestation i n f o s s i l s can sometimes afford a measure of Its degree. Several specimens i n the c o l l e c t i o n show two or more cephala, d i f f e r e n t l y oriented, which exhibit d i s t o r t i o n . In some, the length to 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 other hand may lead to f a l s e length-width r a t i o s due. to the more intense 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 hemi- c y l i n d r i c a l structures such as the axis and g l a b e l l a . Not a l l notes on preservation are gloomy.. One natural cast of Olenellus c f . g i l b e r t 1 ( P l . I I Fig.10) shows two shallow, gently curved depressions tapering forward across the cheek from t h e i r o r i g i n \u00E2\u0080\u009E.at_the base of the palpebral lobes. Their p o s i t i o n and width appear to preclude confusion with \" f a c i a l sutures\", yet they are almost c e r t a i n l y of anatomical s i g n i f i c a n c e . Although 2&. apparently unsegmented, they are thought to he the Impressions of antennules. T h i s o b s e r v a t i o n confirms that of Dunbar, who s t a t e d (1925, p.. 306) that the antennae*1\" of O l e n e l l u s \" . . . a r e simple, p r o j e c t forward, and show no evidence of 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 impossible to gauge the o r i g i n a l shape of a s i n g l e specimen. S i m i l a r i t y of shape depends upon s i m i -l a r proportions of component p a r t s . On a d i s t o r t e d specimen the. r a t i o of length to width may be very m i s -l e a d i n g ; but the r e l a t i v e value of measurements made i n the same d i r e c t i o n tends to be constant f o r a species r e g a r d l e s s of d i s t o r t i o n . Working independently, the w r i t e r found that c e r t a i n c e p h a l i c r a t i o s were of d i a g n o s t i c v a l u e : the o v e r a l l width of the cephalon to that of the o c c i p i t a l r i n g , and the l e n g t h of the o c c i p i t a l and three lobes immediately a n t e r i o r to i t r e l a t i v e to that of the p a l -p e b r a l l o b e s . L a t e r , : t h i s system was modified t o b r i n g i t i n t o l i n e with the methods suggested by Lochman (1947, p . 60). The c e p h a l i c features f i n a l l y u t i l i z e d i n t h i s \u00E2\u0080\u00A2 1 1. S i c 27 connection were: 1. R e l a t i v e p o s i t i o n of midpoint of eye r e l a t i v e to that of g l a b e l l a 1 . (Ibid) 2. Width of cheek from d o r s a l furrow to outside of genal angle r e l a t i v e to width of o c c i p i t a l r i n g . ( 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 four 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 , to that of p a l p e b r a l l o b e s . 4. For the sake of completeness, the t h o r a c i c r a t i o , length of p l e u r a l groove to width of a x i a l lobe at the 2nd segment, i s Included here \u00E2\u0080\u00A2 TABLE I Cephalic and Thoracic R a t i o s Average values of 10 t y p i c a l - specimens of each species Species: 1 2 3 4-O l e n e l l u s eagerensis l e v e l 1.0-1.25 1.5-1*8 0.6-0.8 0 . s c h o f i e l d l behind 1.8-1.9 1.4-1.8 1.2-1.3 0 . c f . . g i l b e r t ! \" 1.6-1>7 1.25-1.35 1.1-1'.2 Paedeumias nevadensis l' 1.7-1.9 1.25-1.35 D.l-1.2 (numbered columns r e f e r to sect ions In the text) SYSTEMATIC POSITION OF OLENELLIDS The f a c i a l suture as such does not appear to be present i n o l e n e l l i d s . But most of them do possess marginal s u t u r e s . The w r i t e r i s i n c l i n e d to 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 other Arthropods shed t h e i r more or l e s s r i g i d e x t e r n a l covering or exoskeleton p e r i o d i c a l l y . To accomplish t h i s ecdysis. i t i s necessary f o r t h i s covering to s p l i t somewhere; and i t 28. i s h i g h l y probable t h a t t h e - . f a c i a l suture was the l i n e a l o n g which s u c h - s p l i t t i n g took p l a c e . There seems however t o be a - tendency to assume t h a t a l l l i n e s which ser v e d t h i s purpose are homologous. T h i s has i n t r o d u c e d unnecessary d i f f i c u l t i e s i n t o the 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 . \" S i nce the accepted method of c l a s s i f i c a t i o n does i n v o l v e f a c i a l s u t u r e s i t seems w i s e s t t o admit w i t h Poulsen (1932) and Resser (1938) the unique p o s i -t i o n of the o l e n e l l i d s and t o ac c o r d them the rank o f an o r d e r . Because O l e n e l l u s . as the f i r s t d e s c r i b e d genus, and one of the most w i d e l y d i s t r i b u t e d , appears t o be f i r m l y e s t a b l i s h e d as t y p i c a l , the c l a s s i f i c a t i o n f o l l o w e d here i n c l u d e s these t r i l o b i t e s i n the order O l e n e l l l d a . GENERIC AND SPECIFIC DISTINCTIONS Resser and Howell (1938) s t a t e t h a t s i n c e t he genotypes o f O l e n e l l u s and Mesonacls. 0. Thompson! and M. vermontana do not show s u f f i c i e n t d i f f e r e n c e s , the names \"Mesonacls\" and \"Mesonacidae\" must be dropped. They p o i n t out t h a t the d i f f e r e n c e between the p o s t e r i o r segments o f these s p e c i e s \" e x i s t s and has some s i g n i f i -cance, but i t i s not now b e l i e v e d to be of g e n e r i c importance\". ( I b i d . p. 217) Since the poor and i n f r e q u e n t p r e s e r v a t i o n o f 29. terminal segments has. l e d i n the past to so. much confusion, i t i s clear that they cannot constitute 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 differences i n the cephalon and thorax must be used also . I t i s believed that s u f f i -cient difference exists between c e r t a i n species of Olenellus to j u s t i f y re-examination of the problem. I f \"Mesonacls\" were r e s t r i c t e d only to such comparatively d i s t i n c t species as 0. eagerensis, M. insolens, M. b r i s t o l e n s i s . and perhaps 0. vermontanus, a majority of the following 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 Olenellus or from Paedeumias. But, since the writer i s dependent on photographs rather than specimens from other l o c a l i t i e s , t h i s proposal i s made very tentatively'. TABLE II Possible Generic D i s t i n c t i o n s Characteristic Paedeumias Olenellus Mesonacls a. Posterior .segments . \"4 ~~ 2-6 . 10 \u00E2\u0080\u00A2 b. Centres: eye to g l a b e l l a (1. p. 27) ' behind behind l e v e l c. 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 d. Longitudinal cephalic . r a t i o (3, p. 27) 1.2-1.4 1.2-1.8 1.5-1.8 e. Lateral.thoracic r a t i o .(4, p. 27) 1.0-1.2 1.2-1.3 0.6-0.8 f . Glabellar shape c y l i n d r i c a l c y l i n d r i c a l \"hour-May taper . .glass\" forward g. Brim, anterior to . g l a b e l l a always sometimes never h. Stalk on hypostoma always never never 1. Intergenal spines always frequently reduced 30. RECOMMENDATIONS FOR FURTHER STUDY 1. A study should 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 of O l e n e l l u s eagerensis are p r e s e n t , one with narrower cheeks, the other w i t h a more enlarged f r o n t a l lobe, than that described i n t h i s paper. This should be checked, 3\u00C2\u00BB 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 p o s s i b l e that O l e n e l l u s g i l b e r t ! i s a '\"form species\" comprising l e g i t i m a t e species 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 . . . that some of the specimens r e f e r r e d by authors to Mesonacls g i l b e r t ! belong n e i t h e r to that species nor even t o Mesonacls. but are d i s t i n c t species of Paedeumias.\" This species should be thoroughly re-examined, 4. As i n d i c a t e d i n t h i s paper, i f the generic 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 fol lowed, at l e a s t one.new genus must be erected 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) This may involve the r e - e x a m i n a t i o n . o f generic 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 III DESCRIPTION OF GENERA-AND SPECIES Phylum Arthropoda Class Crustacea Subclass T r i l o b l t a Order O l e n e l l l d a Family Olenellidae Genus Olenellus H a l l , 1862 Barrandia H a l l N.Y. State Cab. Nat. Hist., 13th Rept. (1860) p. 115. Olenellus H a l l N.Y. State Gab. Nat. H i s t . , 15 Rept. (1862) p. 114. Mesonacls Walcott Am. Jour. S c i . , 3rd ser., v o l . 29, . (1885) p. 328, f i g . 1, 2. Olenellus Walcott U.S. Geol. Surv., B u l l . 30, (1886) p. 162, I65. Mesonacls Walcott U.S. Geol. Surv., B u l l . 30, (1886) p. 158, 165. Olenellus Walcott U.S. Geol. Surv., 10th Ann. Rept. (1891) p. 165 , -633. Mesonacls Walcott-U.S. Geol. Surv., 10th Ann. Rept. (1891) p. 637. Mesonacls Walcott Smithsonian Misc. C o l l . , V o l . 53, no. 6 (1910) p. 246, 261. Olenellus Walcott Smithsonian Misc. C o l l . , v o l . 53, no. 6 (1910) p. 248, 311. Mesonacls Resser Smithsonian Misc. C o l l . , v o l . 81, no. 2 (1928) p. 3 . Olenellus Resser Smithsonian Misc. C o l l . , v o l . 81, no. 2 (1928) p. 5 . Olenellus Resser and Howell, B u l l . Geol. Soc. Amer., v o l . 49, (1938) p. 217, 218. The most recent authoritative work on o l e n e l l i d s i s that by Resser and Howell (1938). U n t i l a great deal more much needed study has been made of the whole order i t i s - c l e a r that t h e i r generic diagnoses of Olenallus 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 writer, faced with a fauna i n which c e r t a i n species assigned to Olenellus show closer a f f i n i t i e s to Paedeumias than to other species placed i n t h e i r own genus, i s bound to suggest a l t e r n a t i v e grouping. I t i s probable that e i t h e r a r e s t r i c t e d genus Mesonacls w i l l have to be revived, or that the genus Paedeumias. w i l l have to be greatly enlarged at the ex-pense of Olenellus; indeed; i t i s possible that both expedients w i l l be necessary. The following generic diagnosis of Olenellus i s summarized and s l i g h t l y modified from Resser and Howell (1938, p. 217). Diagnosis The cephalon i s large; the thorax, of many segments, i s long and tapering; the pygidium i s repre-sented by a small p l a t e . Cephalon usually semicircular, highly convex, with long genal spines. F a c i a l sutures not f u n c t i o n a l . Glabella wide, extending to f r o n t a l rim, either c y l i n -d r i c a l or \"hourglass\" shaped. Of the three pairs of g l a b e l l a r furrows, the f i r s t connects across the middle, setting o f f the rounded f r o n t a l lobe; the second i s frequently reduced to a p a i r of s l i t s , which i n adults 33. f a i l to reaoh the d o r s a l furrow; the t h i r d p a i r of furrows, l i k e the o c c i p i t a l behind i t , f a i l s to connect across the g l a b e l l a . 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 of the f r o n t a l and p a l p e b r a l l o b e s . The brim i s narrow, often only equal to the width of the marginal furrow. Rim v a r y i n g i n width between s p e c i e s , u s u a l l y f a i r l y narrow, widening s l i g h t l y toward the genal a n g l e s . 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 large and, l i k e the p a l p e b r a l l o b e s , may extend almost to the p o s t e r i o r margin. F a c i a l sutures are not present as such, but p o s s i b l y are represented 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 , running from under the eyes toward the genal a n g l e s . Cheeks are large and convex. Intergenal spines often p r e s e n t . Genal spines u s u a l l y l a r g e , but smaller 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 s i z e as the f r o n t a l l o b e , attached d i r e c t l y to a narrow j epistomal plate'* Thoracic segments v a r y i n g i n number, but f i x e d w i t h i n a s i n g l e s p e c i e s , u s u a l l y l o o s e l y arranged. Pleurae 54. s t r a i g h t , sharply curving back to long t a p e r i n g ends. P l e u r a l grooves wide and s t r a i g h t to the fulcrum, where they bend s l i g h t l y l e s s sharply than the p l e u r a e , and begin to contract s l i g h t l y more abruptly than the p l e u r a l terminations* The f u l c r a l angle and tapered terminations increase 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 decreasing l e n g t h of the p l e u r a e . The r e a r seg-ments p o i n t almost d i r e c t l y backward, p a r t l y e n c l o s i n g the large a x i a l spine on the 15th segment. Varying numbers of small 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 often c a l l e d rudimentary because they often 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 segment, a x i a l spines are u s u a l l y 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 confused w i t h Paedeumias. from which i t d i f f e r s \" . . . c h i e f l y i n the p o s i t i o n and s i z e of the g l a b e l l a , i n the wider doublure, and i n the d i r e c t attachment of the hypostoma to the marginal p l a t e , without the s lender s t a l k of Paedeumias\" (Resser and Howell , p . 2 1 8 ) . Genotype: O l e n e l l u s thomnsoni H a l l 1862 35 OLENELLUS o f , GILBERTI MEEK, 1874 F r o n t i s p i e c e ; Plate I I , F i g s . 6-10. This i s one of the commonest, species present i n the Eager Formation. One of the b e t t e r 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 observations of 0 . c f . g i l b e r t l and from statements made by competent workers ( I b i d p . 226) i t may be i n f e r r e d that the presence of a b r i m of considerable 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. I f t h i s i s so, many species now assigned to O l e n e l l u s should be t r a n s f e r r e d to Paedeumias. Of these, 0 . g i l b e r t ! , as f o r e c a s t by Waleott (1910, p . 329) and by Resser (1928, p . 9) should almost c e r t a i n l y be one of the f i r s t . However, s ince f u r t h e r study, both of the type specimens and of the e x c e l l e n t l y 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 to such a step, i t seems wisest 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 t ime. Diagnosis Apart from the presence of a b r i m , whose width v a r i e s from equal to twice that of the r i m , the cephalon conforms to generic d e s c r i p t i o n . Intergenal spines subdued or absent 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 lobes i s masked to a c e r t a i n extent by long, low p o s t - o c u l a r mounds. Marginal 3 6 . and intramarginal sutures present. Rim f a i r l y narrow, but varies s l i g h t l y between individuals j i t widens f a i r l y strongly at the genal angles. Epistomal plate the same width as rim at the front, tapering gently toward the genal angles. Small node or spine on pos-t e r i o r of o c c i p i t a l lobe. Pleurae of t h i r d thoracic segment greatly enlarged making nearly a r i g h t angle at the fulcrum. Single small spines on the posterior margins of a x i a l lobes are traceable forward, progressively reducing i n size from the 14th segment t i l l they die out altogether at the 3rd. The a x i a l spine on the 15th segment i s very large and long, presenting a curious dimpled structure; the minute depressions are arranged i n quincunx. Rudimentary segments were very doubtfully observed on only one specimen; no l e s s than three appear to be present. Cephalic and thoracic r a t i o s are given i n Table I. Relationships The most nearly a l l i e d forms are those assigned to Olenellus g i l b e r t l Walcott, Paedeumias nevadensis (Walcott) and P. c l a r k i Resser. 37. This species d i f f e r s from 0. g l l b e r t l i n having shorter p a l p e b r a l l o b e s , and c e r t a i n i n d i c a t i o n s 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 i n possessing a wider r i m . From P. c l a r k i and P . nevadensls i t d i f f e r s i n having a narrower b r i m , a more expanded f r o n t a l lpbe, and i n l a c k i n g i n t e r g e n a l spines when a d u l t . OLENELLUS EAGERENSIS n . sp. Plate I , F i g s , 1-11* The most s t r i k i n g feature of 0 . eagerensis i s the great width of the axis' . Cephalon i s s e m i c i r c u l a r i n f r o n t ; p o s t e r i o r margin with c l e a r l y developed i n t e r g e n a l angle of about 145\u00C2\u00B0 i n a d u l t s , l e s s c l e a r l y marked i n young specimens. Advanced, f a i r l y small genal s p i n e s , always oblique to the a x i s by an angle of about 20\u00C2\u00B0. G l a b e l l a \"hourglass\" shaped, with s t r o n g l y convex s e m i - e l l i p s o i d a l f r o n t a l lobe touching the r i m . Both f r o n t p a i r s of g l a b e l l a r furrows i n a d u l t s reduced t o s l i t s , the second almost to dimples; i n immature forms these two furrows connect across the middle, but the second p a i r does not extend to the d o r s a l furrow. P a l p e b r a l lobe i s s h o r t , s t r o n g l y arched, i t s t i p extending to j u s t behind the t h i r d g l a b e l l a r furrow. Rim i s very narrow, widening only s l i g h t l y at the genal a n g l e . P o s t e r i o r r i m shallow, 38, widened at the Intergenal 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 outside i n t e r g e n a l angles; even when absent, they are r e p r e s e n -ted by a s l i g h t t h i c k e n i n g of the r i m , which i s j o i n e d by a low r i d g e to the back of the p o s t - o c u l a r mounds opposite the o c c i p i t a l furrow. O c c i p i t a l r i n g wide, with a small p o s t e r i o r s p i n e . Thorax with broad a x i s . P l e u r a l lobes comparatively s h o r t , sharply 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 short s p i n e s . P l e u r a l grooves s h o r t , broad, f l a t , marked off 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 . Pleurae of t h i r d segment not g r e a t l y enlarged; Small a x i a l spines present on a l l t h o r a c i c segments a n t e r i o r to the 1 5 t h ; the l a t t e r spine i s enlarged, but tapers s h a r p l y . Nothing i s known of s e g -ments, or pygidium, p o s t e r i o r t o the 1 5 t h . Cephalic and t h o r a c i c r a t i o s are given i n 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 101. 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 1 0 2 -110. C o l l : : C . G a r r e t t . Type L o c a l i t y : L o c . B. Eager Formation, 6 m i . N . E . of Granbrook, B . C . Geologic Age: Lower Cambrian. 3 9 . Discussion This species of Olenellus shows such s t r i k i n g differences from the genotype, that were the recommen-dations of Lochman (1947) followed, i t would probably be placed i n a d i f f e r e n t genus. Its closest a f f i n i t y to figured species i s to the drawings reproduced by Walcott (1910, p i . 37, Figs. 8-19) from his previous publications (1884, 1886, 1891) purporting to show the young stages of growth of 0. fremontl. The l a t t e r species has been r e s t r i c t e d by Resser ( 1 9 2 8 ) and proven not to possess advanced genal spines. 0. eagerensls d i f f e r s from Walcott's figures i n having a narrower rim, smaller genal spines, shorter anterior lobe, and wider, more evenly tapering palpebral lobes; but i t s s i m i l a r i t y i s apparent i n view of Walcott's own tentative i d e n t i f i c a t i o n of \"0. of. fremontl\" from the Eager Formation (Schofield, 1 9 2 2 , p. 1 2 ) . From \"Mesonacls\" b r l s t o l e n s i s and \"M\". insolens (Resser, 1928) i t d i f f e r s i n having l e s s advanced genal spines, wider intergenal angles, narrower rim, and more rounded f r o n t a l lobe. From 0. vermontanus i t d i f f e r s i n having s l i g h t l y shorter palpebral lobes, narrower rim, 4 0 . sharper i n t e r g e n a l angles, and a s l i g h t l y wider cheek. From other 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 represented i n the c o l -l e c t i o n , and i s based on no l e s s than one hundred cephala ranging from 2.4 to 35 mm. i n w i d t h . I t i s named f o r the Eager Formation i n which i t i s found. OLENELLUS SCHOFIELDI n . sp. Plate I , Figs.\" 12-17. Cephalon s e m i c i r c u l a r , s l i g h t l y t r a p e z o i d a l i n elongated specimens, with an almost s t r a i g h t p o s t e r i o r margin. G l a b e l l a narrow, c y l i n d r i c a l , with expanded h e m i s p h e r i c a l f r o n t a l lobe reaching the r i m . G l a b e l l a r furrows normal f o r genus; second p a i r reduced to s l i t ' s . P a l p e b r a l lobes extremely s h o r t , t h e i r t i p s extending to opposite the f r o n t h a l f of the 3rd g l a b e l l a r lobe behind the f r o n t a l . ' P o s t - o c u l a r nodes very prominent and s h o r t , rounding down abruptly behind t h e i r p o i n t of maximum e l e v a t i o n opposite the back of the 3rd g l a b e l l a r l o b e . Rim very narrow, h a r d l y widening at a l l toward the genal angle. Genal spines s l e n d e r . Intergenal spines present , j o i n e d to back of p o s t - o c u l a r mounds by 41. a s l i g h t l y r a i s e d r i d g e . A minute o c c i p i t a l spine may be present. Thorax t y p i c a l of the genus, but the a x i s , somewhat narrow a n t e r i o r l y , appears to taper r a t h e r g r a d u a l l y . Pleurae angling back sharply to slender t e r m i n a t i o n s . T h i r d pleurae s t r o n g l y enlarged. Small a x i a l spines are present on segments p o s t e r i o r to the f i f t h . - -Rudimentary segments and pygidium unknown. Venation of the cheek surface i s s t r i k i n g l y developed on the l a r g e r forms, c o n s i s t i n g of r a d i a t i n g , i r r e g u l a r l y i n o s c u l a t i n g , r a i s e d l i n e s . The l a r g e s t cephalon assigned to t h i s species i s 32.6 mm. wide by 17\u00C2\u00AB1 mm. l o n g . The r a t i o of width to l e n g t h (1 . 9 ) f o r t h i s specimen i s b e l i e v e d to be a l i t t l e h i g h ; two other cephala o r i e n t e d almost exact ly at 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 . Holotype: 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 202-210. O o l l : . : C . G a r r e t t . Type L o c a l i t y : L o c . B, Eager Formation, 6 mi. N . E . of Cranbrook, B . C . Geologic Age: Lower Cambrian. 42 Discussion The shortness of palpebral lobes, the pro-minent post-ocular nodes, the strongly developed venation and extremely narrow rim serve to d i s t i n g u i s h 0. schofieldi'from a l l other c o r d i l l e r a n species. From 0 . brevoculus i t i s distinguished by . i t s having a narrower rim and r e l a t i v e l y narrower g l a b e l l a , and from 0 . fremontl (s.s.) by the narrow rim, stra i g h t posterior cephalic margin and possession of intergenal spines. This species i s comparatively rare, only ten specimens being d e f i n i t e l y assignable to i t i n t h i s c o l l e c t i o n . I t i s named afte r S.J. Schofield of the Geological Survey of Canada who f i r s t reported the pre-sence of o l e n e l l i d s near Cranbrook. GENUS PAEDEUMIAS WALCOTT 1910 Paedeumias Walcott, Smithsonian Misc. C o l l . , v o l . 53, . no. 6 (1910 p. 304. Paedeumias Resser, Smithsonian Misc. C o l l . , v o l . 81, no. 2 (1928) p. 5 Paedeumias Resser and Howell, B u l l . Geol. Soc. Amer., v o l . 49, no. 2 (1938) p. 225. The redescription of t h i s genus by Resser- and Howell (1938 p 225) expresses the e s s e n t i a l c h a r a c t e r i s t i c s : \"The cephalon- i s large and broad, the thorax has many long-splned segments and terminates 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 probably-had considerable convexity. F a c i a l s u t u r e s 1 are sometimes t r a c e a b l e back of the eyes. G l a b e l l a g e n e r a l l y - c y l i n d r i c a l with the a n t e r i o r lobe tapered 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 wide), i n c r e a s i n g but s l i g h t l y toward.the genal angles. 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 lobe w i t h the r i m , but i t i s p o s s i b l e that t h i s feature d i d not always show on the l i v i n g animal, r e s u l t i n g from compression of the test, on to the\" hypostoma.stalk d u r i n g f o s s i l i z a t l o n . Eyes l a r g e , extending almost to the r e a r m a r g i n ; ! the outer 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 free above the cheek s u r f a c e s . Genal spines 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 p l e u r o n . Intergenal spines present i n , a l l species now d e f i n i t e l y assigned to the genus. The hypostoma i s attached to the marginal or, .more l i k e l y , epistomal p l a t e , by a s t a l k whose l e n g t h equals the distance 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 , having f i v e or more t e e t h oh each side of the median l i n e . The p l a t e to which the hypos-toma i s attached frequently breaks away, sometimes, i n such a manner as to i n d i c a t e a hinged attachment between the genal angles and the i n t e r g e n a l s p i n e s . Thorax apparently has nineteen segments. The f i r s t f i f t e e n are normal i n shape, with the t h i r d g r e a t l y enlarged. A long heavy spine i s present on the f i f t e e n t h p l e u r o n . 1 Back of t h i s the York species shows four r a t h e r simple segments and f i n a l l y a s m a l l p y g i d i a l p l a t e . 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 rearward, are present on the s i x or more segments immediately before the f i f t e e n t h . 1. S i c 44. Surface f a i n t l y l i n e d i n the usual fashion, Paedeumias d i f f e r s l i t t l e from Olenellus except i n the p o s i t i o n of the g l a b e l l a and the stalked hypostoma. Genotype; P. transltans walcott, 1910\" To the above diagnosis l i t t l e can be added, but the palpebral lobes and eyes of at l e a s t one species, P. nevadensis. are short and extend no further back than the o c c i p i t a l furrow* S i m i l a r l y the writer main-tains personal reservations concerning i n t e r p r e t a t i o n of l i n e s back of the eyes as f a c i a l sutures*. PAEDEUMIAS NEVADENSIS (Walcott) ' P l a t e I I , Pigs. 1-5. \" ' Oallavia ? nevadensis .Walcott, 1910 (pars) Smithsonian Misc. C o l l . , vol..53, No. 6 p. 285, p i . 38, Pig. 12. paedeumias nevadensis Resser, (1928) Smithsonian Misc. 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 are: the bl u n t l y tapering g l a b e l l a , short palpebral lobes, exten-ding no further than opposite the o c c i p i t a l furrow, and wide brim, about 3 to 4 times the width of the rim. P=*~nevadensis i s e a s i l y confusible with Olenellus cf. g i l b e r t ! i n the Eager Formation. These species apparently overlap i n width of brim, s i z e of 4 5 . ' f r o n t a l and palpebral lobes, and i n development of a x i a l and intergenal spines. 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 of the Paedeumias type, and at t h i s stage i n the research could, with equal f a c i l i t y , be re f e r r e d to 0. o f . K l l b e r t l . P. nevadensis. or i n some cases to P~. c f . c l a r k i . This gives point to the suggestion that these forms, i f not conspecific; are here i n the process 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 analysis, based on several fea-tures, i s necessary to check t h i s suggestion. 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 . Geol. Soc. Amer., v o l . 49, No. 2, (1938) p. 227. The following diagnosis i s based on Resser and Howell (Ibid) and on personal observation. Entire t r i l o b l t e ovate, with large, semicir-cular, highly convex, t h i n cephalon, which i s usually severely f l a t t e n e d i n adult specimens. Glabella strongly expanded a n t e r i o r l y and touching rim. Dorsal furrow deep on thorax but poorly impressed on cephalon. Glabellar and o c c i p i t a l furrows s i m i l a r to those of 46. O l e n e l l u s . but shallower. O c c i p i t a l r i n g with short s p i n e . Rim wide, i n c r e a s i n g r a p i d l y toward genal a n g l e s . 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 s h o r t , sharply 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, attached d i r e c t l y to epistomal p l a t e . This p l a t e i s wide, and toothed along i t s inner edge. Epistomal and marginal, p l a t e s attached throughout f u l l l e n g t h of the former. Both p l a t e s may be s t r i a t e d ^ but the epistomal p l a t e often shows a r e t i c u l a t e surface 1 . Thorax i n the type species of seventeen s e g -ments, which decrease r e g u l a r l y i n s i z e , except the l a s t two, which are markedly s m a l l e r . D o r s a l and a x i a l furrows deeply Impressed. The f i r s t fourteen a x i a l r i n g s have.short s p i n e s , p r o g r e s s i v e l y longer toward the r e a r . The f i f t e e n t h segment has a very strong a x i a l s p i n e , but the two p o s t e r i o r segments l a c k s p i n e s . Segments n e a r l y s t r a i g h t to fulcrum, with wide p l e u r a l furrows, which taper g r a d u a l l y , terminating b l u n t l y at the fulcrum. P l e u r a l extensions curve backward and taper to 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 p l a t e , with a median r i d g e , surrounded by t i p s of r e a r t h o r a c i c segments1. 47. Surface of e n t i r e t r i l o b l t e coarsely r e t i -c u l a t e , except marginal p l a t e , which i s s t r i a t e d or s c a l y . \u00E2\u0080\u00A2 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 of f e a t u r e s : expan-d i n g g l a b e l l a , normal t h i r d t h o r a c i c p l e u r a e , large 15th spine, and coarsely r e t i c u l a t e s u r f a c e . Genotype: O l e n e l l u s (Holmla) waloottanus. Wanner,. 1901 Rangej Lower Cambrian of North America and Greenland. WANNERIA WALCOTTANA (WANNER) , Plate I I , F i g s . 11-18. O l e n e l l u s (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 '\" \u00E2\u0084\u00A2 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 Walcott, 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 Howell , 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 . 10,.Figs. 8-10; p i . 11. _ Diagnosis: One of the l a r g e s t of the o l e n e l l i d s , up to 17 cm. i n width. Cephalon strongly convex. Marginal 48. furrow deep'. Broad r i m , terminating i n large genal s p i n e s . G l a b e l l a t y p i c a l of genus. Strongly convex f r o n t a l lobe, expanded to one t h i r d width of 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 g l a b e l l a r lobes, r i s i n g sharply towards the r e a r . O c c i p i t a l spine may be p r e s e n t . D o r s a l , g l a b e l l a r , and o c c i p i t a l furrows shallow. P a l p e b r a l lobes deeply e r e s c e n t i c , h i g h l y convex, 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 -t i o n opposite the l a s t g l a b e l l a r l o b e . Marginal sutures as i n O l e n e l l u s . Hypostoma large and d e n t i c u l a t e . Thorax t y p i c a l of genus. F a l c a t e p l e u r a l terminations marked with f i n e , curved, overlapping s t r i a e , roughly transverse v e n t r a l l y and s u b - l o n g i t u d i n a l d o r s a l l y , as i n O l e n e l l u s . P l e u r a l grooves are wide, gently t a p e r i n g troughs, terminating somewhat b l u n t l y at the fulcrum. Segments p o s t e r i o r to the 15th, and pygidium, t y p i c a l of genus. Surface r e t i c u l a t e , the coarseness of the polygonal 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 specimen, not u s u a l l y v i s i b l e on those smaller than' 25 mm. i n w i d t h . More than 100 specimens are present I n the c o l l e c t i o n , ranging i n width from 2\u00C2\u00AB5 mm. to 12 cm. In young specimens the convexity i s s t r i k i n g . During growth the comparative width of the r i m appears to decrease. 49. Immature forms tend to c u r l up; segments posterior to the 12th are usually concealed f o r t h i s reason. The adult W. waloottana from Granbrook seem* to d i f f e r from those i n the eastern part of the continent In two d e t a i l s : hypostomae appear to lack teeth, and spines are absent from the o c c i p i t a l r i n g and from thoracic segments anterior to the 15th. I f these apparent differences are proven to be r e a l , the choice w i l l have to be made between r a i s i n g these specimens- to s p e c i f i c rank, or recognizing that d e n t i c u l a t i o n of the hypostoma i s a feature only of subspeclfic value i n c l a s s i f i c a t i o n . Order Op.isthoparida Superfamlly Corynexochoidae Family .Gorynexochidae Genus Bohnia Waleott, 1916 Gorynexochus\u00E2\u0080\u009E.(Bonnla). Waleott, Smithsonian Misc. . C o l l . , v o l . 64, No. 5 (1916) p. 325. Bonnia Raymond, Amer. Jour. S c i . , 5th ser. v o l . 15, No. 88 (1928) p. 309. Bonnla Resser, Smithsonian Misc. C o l l . , v o l . 95, No. 4 (1936) p. 6. Bonnia Lochman, Jour. Paleontology, v o l . 21, No. 1 (1947) p. 68. \"Granidium: If. Palpebral lobes medium size , back of midline of g l a b e l l a but not quite as f a r back as one-third. 5 0 . 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, convexity; f i r s t two p a i r s of g l a b e l l a r furrows, often 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) width of g label la; . 4 . F i x e d cheeks h o r i z o n t a l or very s i g h t l 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 s s than l e n g t h of o c c i p i t a l r i n g ' . 6 . No f r o n t a l l i m b , a convex f r o n t a l border,, marginal furrow at s i d e s o n l y . Pygidium: 1. Nearly 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 marginal s p i n e s . 2. P l e u r a l lobes same width as a x i a l l o b e , a narrow marginal furrow, a narrow but d i s t i n c t marginal b o r d e r . 3* A x i a l lobe of medium width, - 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 p o r t i o n . \" 1 (Lochman,. 1947 p . 68-69) Genotype: Bathyurus parvulus B i l l i n g s , 1861 Range: Lower Cambrian, North America and A s i a BONNIA c f COLUMBENSIS RESSER . P l a t e I I , F i g s . 1 9 , 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 . 319, p i . 5 5 , F i g s . 7 - 7 c Bonnia columbensis Resser f Smithsonian M i s c . , C o l l . , v o l . 9 5 , No. 4 (1936) p . 9 51. Two poorly preserved c r a n i d i a and one pygidium are present i n the c o l l e c t i o n , conforming to generic description. 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 reference to the works c i t e d , especia-l l y by comparing with photographs by Waleott (1916). Apparently .this :was the form Waleott i d e n t i f i e d as Prototypus seneetus (Schofield 1922, p. 12). 52. .SELECTED BIBLIOGRAPHY Beecher, C.E. (1897) Outline of a natural c l a s s i -f i c a t i o n of t r i l o b l t e s ; Am. Jour...Sci., ser. 4, v o l . 3, pp. 89-106, 181-207. B e l l , G.K. (1931) Disputed structures of the Mesonacidae and.their.significance; Am. Mus. Novitates, no. 475, pp. 1-23. Burling, L.D. (1914) Ear l y Cambrian stratigraphy in.-the North .American, c o r d i l l e r a ; Geol. Surv. Canada, Mus. B u l l , now-2, ppv 93-129. (1916) Paedeumias, and the Me sonacidae with description of a-new species, having a t . l e a s t 44 segments, from the Lower Cambrian of B r i t i s h Columbia; Ottawa Nat.-,.vol. 30, no. 5, pp. 53-58. Deiss, C. (1939) Cambrian formations of south-western Alberta and southeastern B r i t i s h Columbia; B u l l . Geol. Soc. Amer., v o l . 50, pp. 951-1026. (1940) Lower and Middle Cambrian stratigraphy of southwestern and southeastern B r i t i s h Columbia; B u l l . Geol. Soc. Amer., v o l . 51, pp. 731-794. Dunbar, CO. (1925) Antennae i n Olenellus g e t z i . ti.sp.; Am. Jour. S c i . , ser. 5, v o l . 9, -pp. 303-308. Evans, C.S. (1932) Brisco-Dogtooth Map-Area, B r i t i s h Columbia; Geol. Surv. Canada, Sum. Rept., pt. A l l , pp. 160-175. H a l l , J . \" (1859) Trilob-ites of the shales of .the Hudson River Group; Ann.. Rept. N.Y. State Cab. Nat. H i s t . v o l . 12, pp. 59-62. (1862) Supplementary note to the .. thirteenth, report of the regents of the state cabinet; Ann. Rept. N.Y. State Cab. Nat. H i s t , v o l . 15, p. 114. Howell, B.F., et a l . (1947) Terminology f o r describing Cambrian t r i l o b i t e s ; Journ. paleontolV, v o l . 21, pp. 72-76. Keen, A.M. and Muller, S.W. (1948) Procedure i n Taxonomy; ..Stanford Univ. Press'. 53. Poulsen, C. (1927) The Cambrian, Ozarkian and Canadian faunas of.northwest Greenland; Medd. Gronland, v o l . 70, pp. 237-343. (1932) The Lower Cambrian'faunas of . east Greenland; Medd. Gronland, vol.-87, no. 6, pp. 1-66. Rasetti, F. (1948) Lower Cambrian t r i l o b i t e s from the conglomerates of Quebec; Journ. Paleontol., v o l . 22, pp. 1-24. . (1951) Middle Cambrian stratigraphy and faunas of_the Canadian Rocky Mountains; Smithsonian Misc. C o l l . , v o l . 116, no. 5, PP\u00C2\u00AB 1-270. Raw, F. -i (1925) The development of Leptoplas-. tus Salter1 and' o t h e r . t r i l o b i t e s ; Geol. Soc. London,. Quart. Jour'., v o l . . 81, pp. 223--324. (1927) 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. Jour. Sci 1., v o l . 14, no. 78, pp. 7-35; no, 80,.pp. 131-149. . (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 within the group; Geol. Soc. London, Quart. Jour., vol.-92, pp. 236-293. -' i (1937) Systematic p o s i t i o n of the Olenellldae (Mesonacidae); Journ. Paleontol., 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 of -- t r i l o b i t e s a f t e r twenty years; Am. Jour. 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. Jour. S c i . , ser. 5., v o l . 15, pp. 168-170. (1920) The appendages, anatomy, and relationships.of t r i l o b i t e s ; Mem. Conn. Acad. Arts 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 Misc. C o l l . , vol.. 81, no. 2, pp.. 1-14. (1936) Second contribution to nomenclature of trilobites;.Smithsonian Misc. 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 Olenellus zone of. the Appalachians; B u l l . Geol. Soc. Amer., v o l . 49, pp\". 195-248. Rice, H.M.A. (1937) Cranbrook Map-Area, B r i t i s h Columbia; Geol. Surv. Canada, Mem. 207. (1941) Nelson Map-Area, East Half, B r i t i s h Columbia; Geol. Surv. Canada, Mem. 228. Ross, R.J. (1948) Revisions i n the,terminology of t r i l o b l t e s ; Am. Jour. S c i . , v o l . 246, pp. 573-577. Schofield, S.J. (1915) Geology of Granbrook Map-Area, .Br i t i s h Columbia; Geol. Surv. Canada, Mem. 76. (1922)^ Relationship,of the, Pre-Cambrian (Beltian) t e r r a i n to the. Lower Cambrian Strata of,southeastern B r i t i s h Columbia; Geol. Surv. Canada, Mus. B u l l . no. 35* Stubblefield, C.J. (1936) Cephalic sutures and t h e i r bearing on current 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 f . Rev., v o l . 11, pp. 1-30. Swinnerton, H.Hv (1915) Suggestions f o r a revised 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 ; Geol. 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) Invertebrate Paleontology; McGraw-Hill. Waleott, CD. (1886) Second contribution to the studies on the Cambrian faunas of North America; U.S. Geol. Surv. B u l l . 30, pp.. 1-369. (1891) The fauna of the Lower Cambrian or Olenellus zone; U.S.-Geol. Surv., 10th Ann. Rept1., pp. .5H-658. (1910) Olenellus and other genera of the Mesonacidae; Smithsonian Misc. C o l l . , v o l . 53, No. 6, pp. 231-378. 55. Walcott, CD. 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. Misc..Coll., v o l . 64, no. 5, pp. 503-456. Walker, J.P. (1926) Geology and Mineral Deposits of \u00E2\u0080\u009E.Windermere Map-Area, B.C., Geol. Surv. Canada, Mem. 148. '\u00E2\u0080\u00A2 _ . Wanner, A. (1910) A new species of Olenellus from the Lower Cambrian of York County Pennsylvania; Wash. Acad. S c i . P r o c , v o l . 3 , pp. 267-272. 5 6 . PLATE I O l e n e l l u s eagerensls, n . sp. and 0. s c h o f i e l d l , n . s p . ' F i g s . 1 - 1 1 . 0 . ' eagere-nsis n . 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. G T 1 0 2 . 2 . Holotype (XI) showing o c c i p i t a l and a x i a l s p i n e s . U . B . C , No. G T 1 0 1 . 3\u00C2\u00BB 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 to 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 -G T 1 0 9 . (Note: 8 i s a photograph.of a p l a s t e r c a s t . ) 4 . Incomplete specimen showing p o s t - o c u l a r mound \u00C2\u00BB and character of pleurae'. (X2.3) Paratype, U . B . C , No\". GT104. . . 1 0 . Minute cephalon showing t y p i c a l proportions 1 . ' ( X 5 ) Paratype. U . B . C , No;. G T 1 1 0 . . . 1 1 . 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 , . No. GTlir. F i g s . 12-17. 0 !. schof i e l d l . n . sp'\u00C2\u00AB (p. 40) 12, 15, 16, 17, (X1.7, \u00E2\u0080\u00A2 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 cephala, 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 short p a l p e b r a l lobesv Paratypes 1 . U . E . C . , Nos :. GT203 - GT206. 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 s p i n e s . (X2.5) U . B . C . No> GT202. 14'. Holotype (X2.1) showing narrow r i m and a x i s , strong p o s t - o c u l a r node, short p a l p e b r a l l o b e , and veining' . U . B . C , No. GT20I. PLATE I 57. PLATE II Paedeumias nevadensls. 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) F i g s . 1-5. (p. 44) 1. Two small complete specimens (X2.7) with spine on 15th segment and short i n t e r g e n a l s p i n e s . U . B . C . , No. GT301. 2. Very small specimen (X4.7) w i t h at l e a s t 10 t h o r a c i c segments. Note extremely strong i n t e r g e n a l spines, wide brim t r a v e r s e d by r i d g e and enlarged 3rd pleurae 1 . U . B . C , No'. GT302. 3. Elongated specimen (X4.1) with long 15th spine and 3rd pleuraef. Note wide r i m w i t h t r a c e of narrow epistomal p l a t e , and i n t e r g e n a l spines* reduced during growth. U . B . C . , No*. GT303. 5 r. Adult cephala (XI) showing r e d u c t i o n i n width of brim and. i n . development of i n t e r g e n a l s p i n e s . Nos. GT304, GT305'. O l e n e l l u s 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 cast of complete specimen (X4) showing asymmetrical - l ines p o s t e r o - l a t e r a l from eyes, broken epistomal p l a t e and structure 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 j; Specimen with broad rim and brim of intermediate width ( X I ) . U . B . C No. M i l . (Dorsal mold, photographed w i t h l i g h t from bottom r i g h t ) 9 . Cephalon with 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 traces of antennules*. U . E ' . C , No'. GT355'* Wannerla walcottana (Wanner) F i g s . 11-18 (p':. 47) l l 1 . - 16'. Growth stages showing convexity and p r o p o r -t i o n s o f cephala, strong o c c i p i t a l r i n g , character PLATE I I \u00E2\u0080\u00A258, of r i m , and tendency of small specimens to c u r l up. Note mold of Paedeumias on 14.\u00C2\u00BB U . B . C , Nos. GT501 - GT506. (Magnifications 3, 1, 1, 2.7, 4.3, 1, r e s p e c t i v e l y . ) 17*Flattened d o r s a l impression (X0.8) with a s s o -c i a t e d hypostoma and epistomal p l a t e . U . B . C , No. GT507. 18.Large hypostoma (XI) showing s t r i a t e d surface and apparent l a c k of 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 cranidium (X2.5) U . B . C , Nos. GT401, GT402. 4 8 0 O O ' 7 0 0 0 ' 6 0 0 0 ' _ 5 0 0 0 ' . 4 0 0 0 ' -3 0 0 0 ' -2 0 0 0 . IOOO'. Sea-level V CANADA D E P A R T M E N T OF M I N E S A N D R E S O U R C E S HON T.A.CRERAR. MINISTER, CHARLES CAM SELL. DEPUTY MINISTER M I N E S A N D G E O L O G Y B R A N C H JOHN McLEISH, DIRECTOR B U R E A U O F G E O L O G Y A N D T O P O G R A P H Y F.CC.LYNCH. CHIEF ISSUED 1938 12 116\u00C2\u00B0o o' 4945'-L E G E N D O N o< z y o o o o o O o O z Li UJ S o o o N < M O D E R N R E C E N T A N D P L E I S T O C E N E 12 Glacial drift.; silt, sand, gravel. C R E T A C E O U S O R T E R T I A R Y II Granodiorite C A M B R I A N L O W E R C A M B R I A N IO EAGER FORMATION: argillite CRANBROOK FORMATION: qu.artz.Ue, magrvesite U P P E R P U R C E L L S E R I E S GATEWAY FORMATION': argillaceous quartxite, dotoniitic argillite., concretiortary and pisolitic dolomite L O W E R P U R C E L L S E R I E S PURCELL EXTRUSWES: andesitic lava PURCELL INTRUSIVES: diorite sills and dyke* z < DC CO < o UJ Ct CL 5 SIYKH FORMATION: highly coloured argillite and dclornitic argillile KITCHENER FORMATION: green, grey and purple, huff weathering, dolornitic. argdlite ('RESTON FORMATION green, purple and white, argillaceous quartxite ALDRIDGE FORMATION: grey, rusty weal?*/-* ui,, argillite arid argillaceous quartxite. FORT STEELE FORMATION: white quartxite, banded, grey argillite and quartxite, black., limy argillite, grey-green, dolornitic argdlite Drift, covered areas in which bedrock outcrops are tew or tacking Geological, boundary (located, approximate, assumed' Bedding (inclined. vertical, horixontal. overturned) fcxAJ.it (Ijocated, appro-innate. u.s-.v timed) \u00E2\u0080\u0094 \u00E2\u0080\u0094 . Glacial stride .' Geology by C.E.Cairnes. 1932; and HMA.Ricc.193S. 49 30 Contour interval IOO feet Elevations referred to Mean sea-level Height in feet 5 9 / 0 Prospect ; x Mine dump \u00C2\u00A3 | ^ j l Surveyed and reproduced by tin- Hut-ran <>f flrulin/v and Topography. 125\" izo\" S , I 1,, "Thesis/Dissertation"@en . "10.14288/1.0106600"@en . "eng"@en . "Geography"@en . "Vancouver : University of British Columbia Library"@en . "University of British Columbia"@en . "For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."@en . "Graduate"@en . "A Lower Cambrian trilobite fauna from near Cranbrook, B.C."@en . "Text"@en . "http://hdl.handle.net/2429/41178"@en .