68 ROYAL SOCIETY OF CANADA 



The present author accepted this view, put forward on such hi<rh 

 authority, but has since found reason to infer that the conclusion so 

 universally adopted, was not based on a foundation sufficiently wide, and 

 that we may have to go back ])ractically to the arrangement of the Cam- 

 brian Faunas of North America, propounded by Billings in 1864,' in 

 which the succession from below upward is given as : — 1. St. John's 

 [St. John] grou]). 2. Lower Potsdam. 3, Upper Potsdam. By "Lower 

 Potsdam " Mr. Billing.s understood the rocks containing the Olenellus 

 Fauna. In his time, also, the St. John (iroup was known onl}' to contain 

 a Paradoxides Fauna. 



The im})ossibility of finding the genus Olenellus or its accompanying 

 fauna in the strata of the eastern provinces of Canada, below Paradox- 

 ides (which strata were eventually found to contain a considerable fauna 

 of trilobites), led him in 18'J2 to propound the view that Olenellus might 

 be coteraporaneous with Paradoxides but confined to a ditt'erent habitat.^ 

 This surmise was in a sense contirmed by the finding of the fauna accom- 

 panying Olenellus, though not that genus itself, in company with the 

 highest subzone of Paradoxides at Hastings Cove near St. John, in 1896. 



Cui'iously too, the incoming of this fauna is associated with con- 

 ditions similar to those which led to the introduction of the Upper 

 Paradoxides Fauna in Sweden ; for there too, limestones appear in the 

 series, and around the Hunneberg, conglomerates are associated with 

 them. It would seem that in both countries littoral species living where 

 clear waters prevailed, and of a more advanced type of structure than 

 Paradoxides and its companions, crowded out these inhabitants of the 

 muddy bottoms. A change of conditions then, introduced this fauna both 

 in Sweden and Eastern Canada. 



The Protolenus Fauna was also one which flourished best in shallow 

 clear water, hence we are likely to find resembling species between it and 

 the Paradoxides-Dorypyge sub-fauna, which so far as now appears is the 

 horizon of Olenellus (sens, strict.) This parallelism is seen in the num- 

 bers of Agrauloid ti'ilobites in both faunas ; and in Micmacca of the 

 lower fauna (Protolenus Fauna), which is parallel to Bathyuriscus and 

 Dorypyge of the upper (Paradoxides-Dorypyge). 



Further we find that Olenellus in the West of America is linked with 

 Upper Cambrian Faunas rather than Lower. The fauna of Mount 

 Stephen which we have discussed in the preceding article is, according 

 to Mr. Walcott, of the same age as the Prospect Mountain Limestone ; 

 this is shown by the number of species of trilobites common to the two.' 

 But the Prospect Mountain Limestone grades down into shales contain- 

 ing Olenellus, and this Olenellus is accompanied by Olenoides (or Dory- 



1 Gcol. Surv., Newfoundland, 1864, p. 4G. 



2 Tran.s. Hoy. Soc, Can., vol. x., pt. iv., p. 3. 

 ' See U. S. Geol. Surv., liull. 30, p. 31 et seq. 



