102 NEW YORK STATE MUSEUM 



Some oilier observations materially support this conclusion. 

 Foremost of these is the occurrence of C 1 i m a c o g r a ptus 

 schar enbergi in the black limestone. This graptolite, as 

 already remarked in another paper, is a typical form of the 

 lower and upper Dicellograptus zones in Canada, and of the 

 corresponding beds in Great Britain, and is in New York 

 restricted to the lower Dicellograptus zone or Normans kill 

 shale. As the conglomerate bod is intercalated in (bis shale, 

 it is evidenl that the formation of the conglomerate and 

 of the shale are, geologically speaking, contemporaneous, and, 

 as this graptolite of small vertical range occurs also in the black 

 limestone pebbles, the formation of that limestone must also be 

 nearly contemporaneous with, or, more exactly speaking, precede 

 the formation of the conglomerate within the same subdivision 

 of the Trenton limestone epoch. 



The formation of that part of the Normans kill shale lying 

 below the conglomerate bed, and of the black Trenton limestone 

 have, in the waiter's opinion, been synchronous and goiug on in 

 adjacent regions, the black limestone representing the limestone 

 fades corresponding to the shaly Normans kill graptolite farcies. 



The remarkable coincidence of the existence of numerous 

 faunistic elements, strange to the continental Trenton of North 

 America, in both the shales and the black limestone, will be 

 further discussed in the next section, but may be mentioned here 

 as additional argument in favor of the equivalency of the faunas 

 of the Normans kill shales, and of the black Trenton limestone 

 of the conglomerate. 



Faunistic difference between the lower Trenton of New York and 



the west 

 In a previous paper the writer has already discussed the dif- 

 ference in sedimentation and fauna between the lower Tren- 

 ton as represented by the Normans kill graptolite shales of the 

 Appalachian region and lower Canada and the lower Trenton 

 limestone of the regions farther west. 



