304 



Ventral valve flat or gently concave ; area narrow. Dorsal valve de- 

 pressed convex with a wide, shallow mesial sinus nearly the whole length ; 

 cardinal angles compressed , beak apparently incurved down to the hinge 

 line ; area linear. Surface with fine bifurcating striae four to six in the 

 width of one line. 



Width from 10 to 12 lines ; length 6 to 8 lines. The width appears 

 to be in general one-fourth greater than the length. 



This species appears to be allied to 0. platys of the Chazy limestone, 

 but has the ventral valve gently concave or flat, instead of depressed 

 convex. 



Locality and Formation. Stanbridge, range 6, lot 20 ; Quebec group. 



Collector. -T. C. Weston. 



CAMERELLA BREVIPLICATA. (N. sp.) 



Pig. 295. 



Fig. 296. 



Fig. 297. 



Fig. 295. Camere'la breviplicata. Dorsal and side views. 

 296. C. ? costata. Dorsal? valve. 

 29 7. C. polita. Ventral and side views. 



Description. Shell with both valves convex, ovate, greatest width at 

 about one-third of the length from the front, thence narrowed with straight 

 or gently convex sides to the beak ; anterior angles rounded ; front mar- 

 gin usually broadly rounded, but sometimes with a portion in the middle 

 straight. Dorsal valve slightly more convex than the ventral, most tumid 

 in the upper third ; beak closely incurved ; umbo broadly rounded. The 

 ventral valve is like the dorsal, except that it seems to have a small beak 

 a little elevated above the hinge line, and is less convex. 



Surface smooth, from eight to ten short plications at the front margin, 

 usually one-fourth the length of the shell, sometimes less. 



Length of the largest specimen collected 4 lines, width about the 

 same, sometimes a little less. 



Locality and Formation. Stanbridge, range 6, lot 20 ; Quebec group. 



Collector. T. C. Weston., 



