GRAPTOLITES OF NEW YORK, PART 2 I 7 



As this list shows, none oi the species appeal's in every collection, but 

 a few species are mostly present. These arc N e m a g r ap t u s gracilis, 

 Dicellograptus sextans, I ) . furcatus, Diplograptus 

 f o 1 i a c e u s , D . angustifolius, C 1 i m acograptus p a r v u s 

 and C . b i c o r n i s . 



It is further to be noted that, while the association in general may In- 

 said to have been everywhere the same in these localities, still one form is 

 frequently found profusely and as the most common of all in one locality, 

 while in the others it is absent. Thus Dicrano g r a p t u s fa r c a t u s 

 is extremely common at the locality i mile north of Granville and near 

 McDougal's lake, C 1 i m a c o g r a ptus p a r v u s at Pittston corners and 

 Dicranograptus ramosus 2^4 miles north of Middle Granville. 

 To know whether these dominant species will ever become the means of 

 a further subdivision of the zone lies at present beyond the scope of 

 our facts, though in view of the considerable thickness of the rocks 

 carrying the Normanskill fauna a future subdivision seems quite possible 

 and is certainly much to be desired. 



Nemagraptus gracilis has been considered the most character- 

 istic form of the equivalent zone in Europe, and Lapw r orth has also termed 

 this zone in Canada the "zone with Coenograptus gracilis." It 

 is, however, possible, according to Ami's observation, that this species passes 

 also into the next zone. Dicellograptus sextans, Dicrano- 

 graptus furcatus and Clim acograptus parvus are, of the 

 more abundant forms, apparently most strictly bound to this zone and 

 therefore among its best index fossils. 



The genera, which pass but little below and above this horizon, and 

 here distinctly reach their climax by the number of different forms, size and 

 number of individuals, are Nemagraptus, Dicellograptus and Dicranograp- 

 tus. The term Lower Dicellograptus subzone, proposed by Gurley [1892, 

 p. 403] is therefore quite appropriate with the limitation, that, since the 

 next zone is markedly free from Dicellograpti the term Upper Dicello- 

 graptus zone is better replaced by another and the lower zone may be 



