Apbil 1, 1899.] 



KNOWLEDGE. 



81 



aside, because it may never come entirely within our grasp. 

 The real problem at the present day lies in the amazing 

 completeness of the Lower Cambrian fauna, and in the 

 trivial nature of the discoveries that have been made in 

 underlying strata. Setting aside the once famous F.ozodn, 

 which is itself a crystalline metamorphic rock, we know of 

 possible radiolaria in Brittany, obscure brachiopods from 

 the Longmynd, and a slightly more hopeful series of 

 remains from Arizona. • These last include, to quote Mr. 

 Walcott, " a small Patelloid or Discinoid shell, a fragment 

 of what appears to be the pleural lobe of a segment of 

 a Trilobite, and an obscure, small Hyolithes." Lower 

 down, " an obscure Stromatoporoid form occurs in abund- 

 ance." The caution of the above sentences is noteworthy. 

 If the suggested determinations become fully verified, we 

 have here a brachiopod, a trilobite, a pteropod, and a 

 hydrozoan. Similarly uncertain remains have been found 

 in Canada and Newfoundland. North-west India, how- 

 ever, now seems to offer a better field. 



The one thing positive about Precambrian life is the 

 prevalence and antiquity of annelids. Traces of worms 

 have been everywhere recorded ; and other soft-bodied 

 animals have left tracks, which are difficult enough to 

 decipher.! On zoological grounds, worms occupy an 

 august position in the long chain of animal life. ilr. 

 H. M. Bernard:!^ derives such highly organised creatures 

 as the trilobites from a "browsing annelid, with first seg- 

 ment bent round, and lateral projections." The argument 

 connecting the existing crustacean Apus with Ohnt-Uus, 

 and both with their " richly segmented annelidan ancestor," 

 forms a highly instructive chapter in paleontology. In 

 his later paper, Mr. Bernard even aflSrms that " the Crus- 

 tacea can now be linked, step by step, with the chstopod 

 annelids." To him, looking far back into undiscovered 

 faunas, the trilobites themselves appear as " browsing 

 armoured annelids," their ancestors behind them having 

 possessed sixty to seventy segments, and having been 

 genuinely worm-like. But what of the ancestry of these 

 worms themselves ? The pages of the vast Precambrian 

 history must be turned with hesitating slowness. 



The stimulus for research is found at once when we 

 consider the Lower Cambrian fauna. We have there so 

 much to account for — so much that cannot have sprung, 

 full armed, from mother earth. Walcott's review of this 

 fauna,; with his fine series of plates, shows how complete 

 our knowledge has become. To begin with, we have 

 sponges, including the spicular mesh of the well-known 

 Protospongia of Wales ; early types of corals, which were 

 formerly classed as sponges ; hydrozoa, represented by grap- 

 toUtes, and by strange dark markings and siliceous bodies, 

 which are believed to be internal casts of jeUy fish. A few 

 plates of a cystidean, one of the primitive sea-lUies, have 

 been discovered in America. The brachiopods have long 

 been known, including Kiitonjina in our HoUybush Sand- 

 stone, and Linijiddla, an ancestor of the still surviving 

 Linrjula. In Britain, the oldest lamellibranchs are in the 

 Upper Cambrian ; but bivalve moUuscs actually occur in 

 the Olenellus-zone of North America, and form one of the 

 more surprising features of the fauna. If the lamellibranchs 



* C. D. Waleott, "'The Fanna of the Lower Cambrian or Olenellus 

 Zone," Tenth Ann. Report U.S. Geol. Suney (1890), p. 552. 



t Pliotograpliic representations of similar markings in Palaeozoic 

 rocks are well given in Sir W. Dawson's paper in Quart. .Tuurn. Qeol. 

 Soc, Vol. XLVI., p. 595. 



X "On the Systematic Position of the Trilobites," Quart. Journ. 

 Geol. Soc, VoI.'L., p. 430; aUo ibid, Vol. LI. (1895), p. 358. 



§ Tenth Sep. XJ. S. Geol. Survey, pp. 515—658. 



II Walcott, Monographs U. S. Geol. Survey, Vol. XXX. (1898). 



are regarded as degenerate molluscs, their degeneration 

 must have taken place during the Precambrian ages. 



Then we have gastropods, including even Pleurotomaria, 

 which attained its full development in Jurassic times, and 

 which is still represented by four species in the warm seas 

 of the present day. Hyolithes, a common Palaeozoic fossil, 

 is generally treated as a pteropod, but brings us to the 

 verge of the cephalopods, and caps this moUuscan series. 

 Higher animals are represented by the trilobites. 



Of these we already know some fourteen genera, in- 

 cluding the zone-fossil, 

 Olenellus. Species of Oli - 

 nellus have been multiplied 

 of late, and have been 

 named after workers in this 

 difficult Cambrian field. 

 The species here figured 

 (Fig. 1), Olenellus Thomp- 

 soni, was described from 

 Parker's Quarry, Vermont, 

 by .James Hall in 1859, 

 and was made by him,* in 

 1862, the type of the genua 

 olenellus. 



We have, then, in the 

 lowest Cambrian a rich in- 

 vertebrate fauna, primitive 

 in some respects, but stiU 

 far from being primordial. 

 A sea in which fishes had 

 not yet arisen, a world 

 which was dominated by 

 quaint crustaceans some 

 four or five inches long, 

 seems very far removed 

 from the conditions of the 

 present day. But when, 

 on the other hand, we 

 consider the time required 



to differentiate the groups of the moUusca, to encase the 

 cystidean in his plated calyx, to define the genera of the 

 trilobites, so that Oletulhu, " richly segmented," lies side 

 by side with the dwarfed and specialized Aijnostus, then 

 we may see in the Olenellus-zone the beginnings of our 

 modem fatma. The secret beyond that zone spreads out 

 through immeasurable ages. It is written, as it were, on 

 a torn papyrus, the fragments of which lie scattered round 

 about the globe. At length some skilful worker may fit 

 two lines together, though their position in the whole docu- 

 ment may still remain unknown. Yet suf^h a couplet 

 would be for him the triumph of a life-time. 



Fia. 1. — Olenellus Thompsoni. 

 Lower Cambrian. From Parker's 

 Quarry, Georgia, Vermont, U.S.A. 

 From a specimen presented by the 

 U.S. Geol. Surrey to the Koyal 

 College of Science for Ireland. (The 

 head-shield has become pushed 

 back slightly, the large body- 

 segment being in reality the third.) 



Notices of Boofes. 



9 



The Native Tribes of Central Auatralia. By Professor 

 Baldwin Spencer and F. I. Gillen. (Macmillan & Co., Ltd.) 

 ■21s. net. Whoever takes up this book with the hope of 

 finding within its pages a thrilling narrative of life and adventure 

 among the blacks of Centiul Austraha will be grievously disap- 

 pointed. Not so the serious student of anthropologj-, who will 

 discover in it a veritable storehouse of information regarding the 

 manners and customs of the aborigines. It is not often that we 

 meet with so happy a combination of authors : Mr. F. I. GiEen, 

 the special magistrate and sub-inspector of the aborigines at 

 AUce Springs. S. Austraha, has had, through his knowledge of 

 the language, and the confidence he has inspired among the 

 natives, unrivalled opportunities of making himself familiar 

 with their most secret ceremonies and traditions, whilst Professor 



* Fifteenth Report, N. Torlc Cabinet of JS'af. History, p. H4. 



