436 C. K. LEITH 



from the Cambrian are the great preponderance of tube worms, absence 

 or rarity of trilobites, minuteness of the gasteropods, except Patellidae, 

 minuteness of the brachiopods, and the minuteness of the crustaceans. 



Walcott 1 believes the Etcheminian terrane of New Brunswick and 

 Newfoundland called pre-Cambrian by Matthew to be of Lower Cam- 

 brian age. His evidence is : 



i. That the Olenellus fauna in Newfoundland occurs 420 feet 

 beneath the Paradoxides fauna, in the heart of the Lower Cambrian 

 " Etcheminian." 



2. 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. 



3. 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 Matthew) is 3000 feet 

 below the horizon of the Upper Cambrian fauna and 1450 feet above 

 the horizon of the Olenellus gilberti fauna. 



4. That in the southern Appalachians the Olenellus fauna occurs 

 more than 7000 feet below the highest Cambrian fauna known in that 

 region, and fully 2000 feet below a typical Olenoides fauna. 



Matthew 2 makes rejoinder to Mr. Walcott's discussion of the age 

 of the Etcheminian terrane. He argues that Mr. Walcott depends 

 chiefly upon the presence of Coleoloides typicalis as showing the pres- 

 ence of the Olenellus fauna; that this form is not always distinguish- 

 able from Hyolithellus micans, a problematical fossil probably of the 

 tube worms, which, with the brachiopods, is the most striking of the 

 fossils of the lower (Etcheminian) terrane. Moreover, the particular 

 form of Olenellus which Mr. Walcott has found is the Olenellus 

 broggeri, rather than the Olenellus thompsoni, the original Olenellus. 

 Olenellus thompsoni is supposed to occur above the Olenellus broggeri, 

 yet the Protolenus and Paradoxides faunas follow in regular suc- 

 cession to the fauna of the Olenellus broggeri. The question is asked : 

 Where is the fauna of Olenellus thompsoni ? Its absence is supposedly 

 taken as evidence of the presence of the unconformity held by Mat- 

 thew. 



1 Lower Cambrian Terrane in the Atlantic Province, by C. D. Walcott : Proc. 

 Washington Acad. Sci., Vol. I, 1899, pp. 301-339- 



"Mr. Walcott's View of the Etcheminian, by G. F. Matthew : Am. Geol., Vol. 

 XXV, 1900, pp. 255-258. 



