Fossils of the Chazy Limestone. 445 



This species occurs in vast numbers in the Chazy Limestone, 

 on the Island of Montreal, near Cornwall, and at many localities 

 in the valley of the Ottawa. It varies in form and in the number 

 of ribs in the mesial sinus and on the mesial fold. No sufficient 

 distinction has been shewn between the three species above cited. 



Camerella longirostra. (Billings.) 



Camerella longirostra (Billings), Canadian Naturalist and Geologist. 

 Vol. 4, p. 302. 



Fig. 23. 



Fig. 23. — Camerella longirostra. Tbe specimen has the beak of the 

 ventral valve covered by a small fragment of stone, which can- 

 not be removed. 



This species occurs at the Mingan Islands in the Chazy Lime- 

 stone. 



Camerella varians. (N.a.) 



Fig. 24. 

 Fig. 24. — Different views of two specimens of Camerella varians. 



Description. — Sub-triangular; apical angle varying from 75° to 

 100°; valves moderately and nearly equally convex; the ven- 

 tral valve with a wide moderately deep sinus, which becomes obso- 

 lete at less than half the length ; dorsal valve with a corresponding 

 fold ; sides straight from the beak for one-half or two-thirds the 

 length ; front angles rounded ; front margin straight or gently 

 convex ; two to four short rounded ribs in the sinus and one or 

 two on each side ; three to five on the mesial fold and one or two 

 on each side. These ribs become absolete at about one-third or 

 one-half the length, and all the upper part of the fossil is smooth ; 

 beaks small sub-equal ; that of the ventral valve a little more 

 prominent than the other, and with apparently a small triangular 

 foramen beneath it. Beak of dorsal valve incurved ; Length four 



