CONCLUSIONS CONCERNING LOWER DEVONIC 269 



This difference is shown in the abundance of pelecypods and the pres- 

 ence of Goniatites, while in the finest sediments, the slates, an abundant 

 and varied local fauna of crinoids and starfishes is present. 



The Erbray fauna described by Barrois may be the equivalent of the 

 Oriskany or of the Upper Oriskany and Cauda-galli. In any event, it 

 appears to be younger than the typical Hercyn and not as young as the 

 Lower Coblenzian. 



The latter does not appear to the writer to be the equivalent of the 

 Oriskany, as stated by Freeh, but brings to mind some portions of the 

 Upper Helderberg. It may represent either the Cauda-galli fauna, which 

 as such is there unknown, or the Schoharie grit. In any event, it seems 

 clear that the Upper Coblenzian has a fauna which American paleon- 

 tologists may safely conclude to be very much like that of the Hamil- 

 ton, although it probably is not quite so recent. 



American Lower Devonic* 

 helderbergian subdivisions^ 



This series of strata is generally known as the Lower Helderberg group, 

 and " has been so termed from its very complete development along the 

 base of the Helderberg mountains, constituting in this part of New York 

 an important fossiliferous group. In some parts of the Helderberg moun- 

 tains, and along the Hudson river at Rondout, and at Schoharie and 

 elsewhere, the lowermost beds of this group [Tentaculite or Manlius lime- 

 stone] rest directly on the Waterlime beds, which we regard as the 

 uppermost member of the Onondaga salt group." J 



The Helderbergian series in New York reposes on the Manlius (Ten- 

 taculite) limestone, and in places begins with a thin mass of limestone 

 containing Stromatopora, which is known as the Stromatopora lime- 

 stone. The next persistent horizon is the Coeymans (Lower Pentamerus) 

 limestone, "charged with great numbers of the broken shells of Penta- 



* A map giving the known distribution of the Helderbergian and of the Cayugan and Niagaran to 

 1874 was prepared by Professor James Hall, and will be found accompanying a paper entitled " The 

 Niagara and Lower Helderberg groups ; their relations, and geographical distribution in the 

 United States and Canada." See Twenty-seventh Ann. Rept. N. Y. State Mus. Nat. Hist., 1875, 

 pp. 117-131. 



f The terminology here adopted is that of Clarke and Schuchert, Science, vol. x, December 15, 

 1809, pp. 874-878. It is as follows : 



f Oriskanian. Oriskany beds. 



f Kingston beds (= Upper shaly limestone). 

 Eodevonic-J Helderbergian -j Becraft limestone (= Upper Pentamerus limestone). 



j New Scotland beds (= Delthyris shaly limestone). 

 L [Coeymans limestone (= Lower Pentamerus limestone). 



J Hall ; Paleontology of New York, vol. iii, 1859, p. 33. 



