305 



CaMERBLLA ? COSTATA. (N. Sp.) 

 Fig. 296. 



Description. — Broad ovate, greatest -width about the mid-length, uni- 

 formly convex, -with from ten to t-welve strong, angular undivided ribs, 

 ■which extend to the beaks. 



The best preserved specimen of this species that has been collected, is 

 partly imbedded in the matrix. It is transversely ovate or sub-circular, 

 the -width one-fourth greater than the length, the sides and front uniformly 

 rounded, rather strongly convex, the greatest elevation at one-fourth the 

 length from the beak ; umbo broadly rounded. It appears to be a dorsal 

 valve. 



Length 6J lines ; width 8 hnes. 



It is quite uncertain that this species is a true Camerella. It may be 

 congeneric -with Poramhonites Ottawaensis (ante, p. 240). 



Locality and ^ormaiion.— Stanbridge, range 6, lot 20 ; Quebec group. 



Collectors. — J. Richardson, T. C. Weston. 



Camerella polita. (N. sp.) 



Fig. 297. 



Description. — Shell ovate, smooth and moderately convex, greatest 

 ■width at about one-fourth the length from the front margin, thence taper- 

 ing -with gently convex sides to the beaks ; front angles and margin rounded. 

 Dorsal valve most convex just in front of the umbo ; beak incurved do-wn 

 to the hinge. Ventral valve less convex than the dorsal ; beak small, 

 pointed, a little elevated above the hinge. 



Surface smooth. 



Length of largest specimen collected 3 lines ; -width about the same. 



This species has nearly the same form as C. brevipUcata, but differs 

 therefrom in being smooth, in being less convex, in having the front mar- 

 gin thinner and usually more rounded. The form varies from ovate to 

 sub-circular. The young individuals of C. brevipUcata have t-wo or three 

 incipient folds in the front margin by -which they may be readily dis- 

 tinguished from this species. 



Locality and Formation. — Stanbridge, range 6, lot 20, and on the 

 upper end of the island of Orleans ; Quebec group. 



Collectors. T. C. Weston, E. BilUngs. 



