76 AMERICAN JOURNAL 



gin nearly straight in the midflle ; disk ornnmented with minute 

 and very closely arranged lines. Length 1| in. Height f in. 

 The figure represents the hinge of the right valve. Left valve 

 unknown. 



CAMPTONECTES, Agass. 



C. BuRLiNGTONENSIS, Gabb, {Pecten). 



I have found the shell and sculpture of this species, which 

 prove it to be a Camptonectes. 



LEPTOMYA, Conrad. 



Amer. Journ. Conch, vol. iii, p. 15. 



This name having been previously applied by H. and A. 

 Adams to a genus of the family Tellinida', I substitute the 

 name of Periplomya. This genus appears to connect Anatina 

 with Periploma. 



PI. 3, fig. "10, represents the hinge of left valve and the tooth 

 of the opposite valve. 



INOCERAMUS. 



/. pcculiaris, Conrad, Amer. Journ. Conch, vol. v, p. 43, pi. 

 1, fig. 13. This shell should probably be referred to Cercomya, 

 Agassiz. 



VENERID^. 



ARTENA, Conrad. 



Triangular, thick ; surface with acute, concentric, prominent 

 ribs ; hinge with three cardinal teeth in the right valve, two of 

 them diverging, distant, the anterior one under the apex, robust, 

 direct, curved ; left valve with three diverging distant teeth ; 

 lateral tooth very small, pyramidal ; pallial sinus very small and 

 angular. 



Cythcrea staminea, Conrad, Miocene Foss., pi. 21, fig. 1. 



This genus is readily distinguished from the other genera of 



the family by one thick anterior tooth in the right valve instead 



of the two approximate teeth o{ Mer-etrix, Oaryatis, &c., and by 



the two distant, thick, nearly equal teeth of the opposite valve, 



. and also by the very small pallial sinus, the exterior ribs, &c. 



The species is triangular, very ventricose, slightly contracted 

 posteriorly, and between the ribs are close, minute, rugose, con- 

 centric lines umbonal slope terminal, angular ; posterior slope 

 depressed, lunule condate. 



A. UNDULA.TA, Conrad. 



Description. — Subtriangular, profoundly ventricose ; disk un- 



