GRAPTOLITES OF NEW YORK, PART 2 39 1 



aceus Murchison, described as belonging to the hitter species. Hut the 

 writer added in his drawings the apertural spines which, though rarely, were 

 observed in some of the Dolgeville material. This gave Freeh occasion to 

 point out in the Letkaea Palaeozoica that the colonies could not belong to 

 D. foliaceus, which is a spineless form and the)- were by him united 

 provisionally with G. whitfieldi. Not until the splendidly preserved 

 graptolites from the Utica shale of the Rural cemetery near Albany came 

 into the writer's hands, did he become aware of the presence of this St John 

 species in the Utica rocks of New York. 



Ami, however, had before this recognized the wide distribution of G. 

 q u a d r i m u c r o n at u s in the Utica shale of Canada, as is evinced by his 

 fossil lists. 



There is no doubt that Vanuxem, Emmons and Hall had also this form 

 before them, when they cited Graptolites "den tat us" as the most 

 common and characteristic graptolite of the Utica shale of the Mohawk 

 valley in their respective district reports. Of this fact we had an oppor- 

 tunity to convince ourselves by inspection of some of the old types of the 

 First Geological Survey collection now in the American Museum of Nat- 

 ural History. One of these from the Utica shale of Oxtungo creek, in the 

 Mohawk valley, is figured by Hall as D. prist is on plate 72, figure id. 



That D. foliaceus to which the synrhabdosomes from the Utica 

 shale had been first erroneously assigned, possesses colonies of the same 

 complex structure, is shown by the synrhabdosomes figured in this volume. 



The failure to recognize G. quadrimucronatus in the Utica 

 shale of New York is due to still another circumstance, namely, to the fact 

 that the specimens from the New York rocks in no case reach the large 

 dimensions of the types from Lake St John and altogether represent a 

 smaller variety and in the Lorraine beds a different mutation ; they do not 

 only differ in their general dimensions, but also in the number of thecae 

 within a certain space ; the Lake St John types possessing quite uniformly 

 22 to 23 thecae within an inch or 25 mm and those from the Utica shale of 

 the Mohawk valley 26 to 28 thecae. In the Lorraine specimens this differ- 



