FAUNA OF THE HERCYN 261 



Devonic. The great abundance of Phacops is characteristic of European 

 faunas, and is in harmony with Lower Devonic development. The 

 Hercyn trilobites are unmistakably of Devonic age, and seem to find 

 their nearest relatives in the Lower Helderberg, but apparently more 

 directly in the Lower Oriskany. 



The presence of large fish spines and teeth in the Hercyn is strongly 

 indicative of the Devonic, as well as of a development younger than 

 anything known in the Lower Helderberg, and is more in harmony with 

 the American Corniferous. Moreover, these Hercyn fish remains do not 

 agree with those from the Siluric of England. 



There is nothing in American Lower Devonic horizons to be compared 

 with the Goniatite development of the Hercyn. These shells do not 

 make an abundant appearance in American faunas until well into the 

 Middle Devonic, and they give the Hercyn a strong and unmistakable 

 Devonic aspect.* 



The gastropods of the Hercyn point to the Lower Helderberg, but it 

 should be borne in mind that these are nearly all capulids. Their size 

 and the abundance of species, however, will also agree with the Oriskany 

 age. The pelecypods are younger than the Lower Helderberg, and since 

 but very few Oriskany species of this class are known, no direct compari- 

 sons can be instituted. The supposed occurrence of a typical Siluric 

 graptolite zone near the top of the Hartz Hercyn gave it a very ancient 

 aspect and a very remarkable life combination. However, from the 

 work of Tullberg and Denckmann, it is now known that this zone is of 

 Siluric age.f 



From the foregoing review of the typical Hercyn fauna it is clear that 

 while it contains a number of Siluric types, yet its general develop- 

 ment, particularly the large size of many of its individuals, is not to be 

 correlated directly with the Lower Helderberg. On the whole it appears 

 to agree best with the Oriskany. If, in this connection, it is borne in mind 

 that the Upper Oriskany is everywhere a shore deposit — coarse sands and 

 shales — and has a decidedly littoral fauna, while the Hercyn is derived 

 from limestone (the Goniatites indicating deeper water), one of the causes 

 for the marked difference in these faunas is made apparent. On the 

 other hand, the Lower Helderberg fauna, while not of a very deep sea, 

 is deeper than the Oriskany, and if the former is of the same age as the 

 Hercyn, then more harmony might be expected than exists between 

 them. These various reasons result in the conclusion that the Hercyn 

 fauna is to be correlated rather with the Oriskany than with the Lower 

 Helderberg. Freeh would place it a little higher, because he regards it 



*See remarks on the Goniatites of etage F 2 , Konieprussian of Bohemia, p. 265. 

 fSee Freeh : Lethsea geognostica, 1 Theil, 2 Band, 1897, pp. 117, 193. 



