FOSSILS FROM DIVISION I). 



505 



iug lines. On the weathered surface the limestone often appears to be a 

 conglomerate ; in other exposures these conglomerates are replaced by 

 measures of nearly pure limestone, separated from each other by beds of 

 magnesian limestone. 



This division, D, is particularly fossiliferous, the larger number of fossils 

 in the formation being found here ; the purer beds of limestone from bottom 

 to top bearing them. The following 35 genera, gathered from various ex- 

 posures of the division, are represented by species varying in number from 

 one to ten : 



Triplegia 



Orthls 



Holopea 



Loj)hospira 



Bellerophon 



Maclurea 



Piloceras 



Asaphus 



Cryptozodii 



Leptama 



Metoptoma 



Trochonema 



Murchisonia 



S abilities 



Orthoeeras 



Lituites 



Amphion 



Calathium 



Streptorhynchas 



Triblidium 



Pleurotomaria 



Euomphalus 



Calaurops 



Cyrtoceras 



Nautilus 



Havpes 



IAngula 



Hemipronites 



Clisospira 



Rhaphlstoma 



Ecculiomphalus 



Ophileta 



Gomphoceras 



Bathyurus 



Ribeiria 



The total thickness of division D is 375 feet. 



Division E has fine-grained magnesian limestone in beds one or two feet 

 in thickness, weathering drab, yellowish, or brown. Occasionally pure lime- 

 stone layers occur, which are fossiliferous. Rarely thin layers of slate appear, 

 which also are sometimes fossiliferous. 



Here, as in D above, we have observed Murehisonia, Euomphalus, Ortho- 

 eeras, Lituites, and Bathyurus. To them are to be added two genera of 

 encrinites represented by columns aud plates, together with Strophomena, 

 Bucania, Primitia, and Stenopora — six genera not previously mentioned — 

 making in the whole forty-one geuera for the Calciferous. 



Division E has a thickness of 470 feet. 



For all the divisions of the formation we have a total of 1,800 feet. 



Sections. 



Exposures at the various points offer opportunity for making sections ex- 

 hibiting the character and thickness of the rocks of the formation. Of the 

 sections observed and measured, only one or two can be described somewhat 

 in detail ; the others, though in almost every instance presenting some in- 

 structive features, must for the present be passed with a few words. 



