CLINTON OROTTP. 



301 



Genus BEYRICHIA (M'Coy). 



This fossil body has been very appropriately separated by Mr. M'Coy from Agnostis, to 

 which such bodies have heretofore been referred. 



We have three or four species of this in our successive groups, beginning with the Clinton 

 group. 



668. 1. BEYRICHIA LATA. 



PL. A LXVI. Fig. 10 a -e. 

 j^gnostus latus. Vanuxem, Conrad, Rep. N. Y. Geology. 



Semioval or subreniform, unequally trilobate or trinucleate ; on one valve an oval subcentral 

 lobe reaching more than half way across, with a depression on each side, beyond which the 

 surface is elevated ; ventral margin bordered by a narrow defined rim ; on the other valve 

 a depression corresponding to the lobe, and the surface elevated on either side ; surface 

 granulate] 



We know nothing of this species, except from casts in ferruginous slate and sandstone, or 

 equally ill-defined specimens in iron ore. In the best preserved specimens, the surface appears 

 to have been granulate or tuberculate. 



Fig. 10 a. A fragment of ferruginous slate, covered with the separate valves of this fossil. 



Fig. 10 h. A valve having a subcentral depression. 



Fig. 10 c. A valve with a subcentral lobe or nucleus. 



Fig. 10 d, e. The interior of the shell, or impression made by the cast. 



Position and locality. In the ferruginous shale associated with the iron ore at Wadsworth's 

 quarries, and in the ferruginous sandstones below, at New-Hartford, Oneida county ; in nu- 

 merous localities in the same position farther west, and in the green shale of the group at 

 Sodus and Rochester. 



