304 



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

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

 cardinal angles compressed , Leak apparently incurved down to the hinge 

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

 width of one line. 



AVidth 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. /ila/i/s of the Chazy limestone, 

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

 convex. 



Locality/ and Formation. — Stanbridge, range <J, lot 20 ; Quebec group. 



C<jllector.—^il. C. Weston. 



Camerella ereviplicata. (N. sp.) 



Fig. 295. Fig. 296. Fig. 297. 



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

 296,— C? costata. Dorsal? valve. 

 29'?. — C. polita. Ventral and side views. 



Description. — Shell with both valves convex, ovate, gi-eatest 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 portifin 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 bke 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 mai-gin, 

 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. 



