256 



REPORT ON THE STATE CABINET. 



and along this line the black and dark colored graptolite schists, alterna- 

 ting with coarser beds, have collected in much greater mass than in any 

 other part of its extent. In the northwestern counties of New York, 

 Jefferson and Oswego, where the formation has a thickness of more than 

 a thousand feet, the graptolites are comparatively few in species, and not 

 of common occurrence. The gradual attenuation of the rocks of this 

 formation towards the west is marked by the extreme paucity of grapto- 

 litic forms. 



The graptolites of the Clinton strata have not, to my knowledge, been 

 found beyond the limits of Western New York ; and both their horizon- 

 tal and vertical range is very restricted. The' graptolitic forms of the 

 Niagara formation (Dicttonema and Inooaulis) are very limited in their 

 geographical extent. 



The DiCTYONEMA of the Upper Helderberg and Hamilton formations are 

 known to occur in New York and in Ohio ; and in the northwest a species 

 has been found in the Upper Helderlaerg limestone on Mackinac Island. 



This distribution of the Graptolitidge, as well as their general associa- 

 tion with other fossils, together with the nature of the sediments, would 

 indicate the existence of quiet water and proximity of the coast-line as 

 their habitat, and as the zone of their greatest development. 



VERTICAL DISTRIBUTION OF THE GENERA OF THE FAMILY OF GRAPTOLITIDGE. 



GENERA. 



e 



s 



p 



3 



o 



« >; 



1 

 c 



o 

 3 



M 



•3 



1 



a 

 o 



C3 



i 



-a 

 c 

 o 

 c 

 O 



,2 

 -3 



-s 



"3 



p. 

 &. 

 1= 



a 

 o 



1 



C 

 3 

 S 



3 



2 



1 

 a 

 Q 



Graptolithus — f 



Sub-genera Monoprioii, etc. 



Sub-genus Diplograptus . , , 



Climacograptus 



Dicranograptus 





* 

 * 

 * 



* 



# 



* 

 * 

 * 

 » 



* 

 * 



* 



* 

 * 



* 

 * 

 * 



* 

 # 





* 

 # 



* 

 # 







* 



* 











.. j .. 

 . . 1 ... 







T)pndro"'ra'Dtiis 



* 





T^iotvonema 





PtilooTaDtus 





Thamnograptus 



Rastrites 



Inocaulis 



Buthograptus 



Oldhamia .'' 









t For subdivisions under this head see pige" 251 and 260 



