236 CONTRIBUTIONS TO CANADIAN PAL/EONTOLOdY. 



small 8j)ecimen8 in a piece of limeatone ; and Peace Eiver, at Ver- 

 milion Falls, E. (r. McCounell, 1889, one adult and nearly perfect 

 specimen, all of which are pmbably referable to this species. The 

 only adult specimen is certainly " much less ventricose than C. Eudora " 

 of the Chemung sandstones of the State of New York, and approaches 

 more nearlj' in lateral outline to 0. planirostrata. Its dorsal valve is 

 much flatter than the ventral, and its greatest breadth is, if anything, 

 rather behind than in front of the midlength. 



Xewberria, Hall, (Gen. Xov,) 



"Diagnosis. — Shells elongate-ovoid, having the general contour and 

 external aspect of Eenssel.eeia and Amphigenia, but without the 

 strongly radiate-striato surface of the former genus. The convexity of 

 the valves is greatest in the umbonal region, and the surface is dis- 

 tinctly flattened over the lateral slopes, leaving the median portion of 

 the valves very prominent. 



The pedicle-valve has the rostrum produced and incurved ; the apex 

 truncated by a circular foramen ; deltidial plates not determined. The 

 teeth are comparatively small, projecting forward and gently upward, 

 free at their extremities, and suppoi-ted by narrow dental plates, which 

 join the interior of the valve above the middle of its depth and are 

 continued forward as slender ridges upon the inner surface, which 

 gradually mei-ge into the shell. 



In the bottom of the rostral and umbonal cavity there is a broad, 

 scarcely defined muscular area, from which radiate a series of vascular 

 ridges and depressions: the strongly marked ])air of diductors are 

 situated posteriorly, just within this muscular area ; lying in front of 

 these is a single (rarely subdivided) elongate adductor impression 

 which often extends forwards to the centre of the shell. 



Ori each side of the muscular impi'cssions is a thickened triangular 

 area, very narrow at its origin in the umbonal i-egion, widening an- 

 teriorly and produced into iwo divergent furrows (foui- in all) which 

 extend over the pallial region in some instances almost to the anterior 

 margin. 



In the brachial valve tbei-e are two short diveig-ent crural plates, 

 which are not united at their bases to foi-m a hinge plate as in Eens- 

 SEL^RiA, A low median ridge arises between them, jiassing for a short 

 distance along the bottom of the valve, separating the obovate narrowly 

 flabelliform muscular scars of the adductor muscles. These sears are 

 characterized by the stiong striation of their surfaces. 



