,89,. THE STORY OF OLENELLUS. 345 



gneiss, he still regarded the Torridon sandstones as Devonian ; but 



Murchison soon after referred these enormous masses, the bulwark of 



the west highland coast, to the Cambrian System. Professor Judd 



has, we believe, in his teaching uniformly regarded them as Pre- 



cambrian, an opinion now completely justified. 



The Longmynd Series also gains in antiquity by the discovery of 



Olenellus callavei at a higher level; and it has been unhesitatingly 



placed as Precambrian by Professor Blake. Dr. Hicks (23) has 



claimed as Olenellus, from their characteristic surface-ornamentation, 



certain trilobitic remains from rocks some 3000 feet below the 



Menevian at St. David's ; and he gives us in consequence a 



classification that may be stated thus : — 



TT /- u • ' Tremadoc Series. 



Upper Cambrian -, . , ^, 



{ Lingula Flag ,, 



Middle Cambrian \ Menevian .. 



y Solva ,, 



Lower Cambrian Caerfai ,, 



The triple palaeontological division of the Cambrian into the 

 Olenellus, Paradoxides, and Olenus zones is thus arranged for and 

 .accepted in Great Britain ; Professor Lapworth (20, p. 533) would 

 •call the three divisions Taconian (the Olenellus-zone), Menevian (or 

 Paradoxian) and Olenidian ; and doubtless there will be some 

 ■discussion and rectification of the limits of each division. Mr. 

 Walcott (21, p. 376) already asks us to place half the Tremadoc 

 Series in the Ordovician ; and the story of Olenellus, so far as it has 

 gone, is not calculated to give us confidence in a resting stage in 

 classification. However grateful we may be for the literature 

 showered on us, there is one severe critic (25) who would have 

 preferred results to dissertations. The open country has been 

 appealed to, the first and final arbiter in stratigraphical determination ; 

 discovery must precede discussion, and^ we are on the eve of notable 

 •discoveries in the Olenellus-beds of many lands. It is, after all, the 

 Olenellus-fauna that should attract us, rather than any single genus ; 

 and its richness will be seen by all who examine Mr. Walcott's 

 comprehensive memoir (19). We may in any case be sure that the 

 roots of any genealogical trees that we may casually construct will 

 be found to reach far down into yet more fascinating Precambrian 

 zones. 



REFERENCES. 



1. Emmons, E. — The Taconic System. Albany, 1844. 



2. Hall, Jas. — Palaeontology of New York, vol. i., 1847. 



3. Nicol, Jas. — On the Red Sandstones of the N.W. Coast of Scotland. Quart. 



Journ. Geol. Soc. London, vol. xiii., p. 17, 1857. 



4. Hall, Jas. — Twelfth Annual Report, New York Cabinet of Natural History, 



1859. 



5. Hall, Jas. — Thirteenth Annual Report, New York Cabinet of Natural History, 



i860. 



6. Hall, Jas. — Supplementary Note to Thirteenth Report. Fifteenth Report 



N.Y. Cab. Nat. Hist., 1862, p. 114. 



