LOWER CAMBRIAN TKRRANE 337 



terior marginal fold, which has a functional meaning. Though 

 not found at St. John, these trilobites are evidently character- 

 istic of the Protolenus fauna series ; they occur with it at Attle- 

 borough and Conception Bay ; but they are also a common 

 constituent of the Cambrian fauna at Troy, N. Y. ; it seems there- 

 fore highly probable that the Troy fauna in part at least, belongs 

 to the Protolenus zone, but with considerable variation from the 

 typical facies. The fauna is found in its integrity only. in the 

 areas over which the Etcheminian fauna is known to be spread.' 



The latest expression of his views of the Olenellus fauna * in 

 the west of America' is that it is linked with Upper Cambrian 

 faunas rather than Lower. ^ 



Of Olenellus as he restricts it he says : 



To us therefore it seems that the appearance of Olenellus 

 (sens, strict.)^ in the Cambrian Faunas of America marks the 

 irruption of a new group of forms that ousted the typical fauna 

 of Paradoxides, which may be considered to have reached its 

 culminating point in the faunas of P. Tessini and P. Davidis. 

 These would be the conditions in Atlantic North America. 

 Further west the Olenellus Fauna appears in most places to have 

 invaded continental areas, as it is preceded by beds of quartzite 

 and sandstone : and hence all the earlier Cambrian including 

 the Protolenus and Paradoxides Zones exhibit no faunas in those 

 regions.'* 



As against all the above-quoted and many other arguments, I 

 can only state : 



{a) That the Olenellus fauna in Newfoundland occurs 420 feet 

 beneath the Paradoxides fauna, in the heart of the Lower Cam- 

 brian ' Etcheminian.' 



{h) That fragments of the fauna are found 460-480 feet below 

 the Protolenus fauna in the ' Etcheminian' of the Hanford Brook 

 section of New Brunswick. 



(<:) That in the undisturbed, unbroken Highland Range section 

 of Nevada the Olenellus fauna is 4450 feet below the Upper 

 Cambrian fauna, and that the Olenoides (Dorypyge fauna of 



»Loc. cit., p. 55. 



* Fragments of the Cambrian Faunas of Newfoundland: Trans. Roy. Soc. 

 Can., 2d ser., Vol. V, 1S99, Sec. IV, p. 68. 



^"As represented in O. thompsoni, O. gilberti, O. iddirigsi, O. lapworthi, 

 and O. reticulatus.'" Annals N. Y. Acad. Sci., Vol. XII, 1899, p. 55. 



* Fragments of the Cambrian Faunas of Newfoundland : Trans. Roy. Soc. 

 Can., 2d. ser.. Vol. V, 1899, Sec IV, p. 69. 



