420 VENERIS. 



Genus CRYPTOGRAMMA, Morch. 



Shell triangular, ventricose, produced and beaked be- 

 hind. Hinge composed of two primary teeth in the left 

 valve, the anterior conical, acute, and sub-recurved, the 

 hinder linear, parallel, and under the lozenge ; and two 

 primary teeth in the right valve, the anterior compressed, 

 erect, and obtuse, the hinder triangular and decumbent ; 

 lozenge small, crenulate within. Pallial line with a shal- 

 low, triangular, nearly obsolete sinus. 



Syn. Anomalocardia, Schum., not Klein. Triquetra, 

 B lain v., not Klein. 



Ex. C. flexuosa, Linnceus, pi. 107, fig. 4, 4, a. 



The animal of Crypto gramma is unknown ; the shell is 

 thick, solid, triangular and wedge-shaped, without con- 

 centric lamellae ; the internal margin of the valves is cre- 

 nate; there are no anterior lateral teeth, and the cardinal 

 teeth are triangular. 



Species of Cnjptogramma. 



flexuosa, Linn. squamosa, Linn. 



impressa, Hanley. subimbricata, Sow. 



macrodon, Lam. subrugosa, Sow. 

 rostrata, Sow. 



Genus CHIONE, Megerle von Mublfeldt. 



Mantle-margins plicato- dentate ; siphons, short, broad, 

 unequal, and united at the base, the branchial with two 

 rows of cirrhi, the anal ciliated. 



Shell ovately triangular, more or less thickened or sub- 



