428 VENERIUM. 



Pallial impression posteriorly sinuated; sinus narrow, semi- 

 oval. 



Si/n. Cuneus, Miihlf., not Da Costa. Meroe, Schum. 

 Cytherea, Sow., not Lam. 



Ex. S. Meroe, Linnaeus, pi. 108, fig. 3, 3, a. 



The animal of Sunetta is unknown. The shell is trans- 

 versely ohlong, the lunule very deep with sharp edges, the 

 internal margin of the valves is crenate, and the hinge has 

 the hind cardinal tooth torn and cross-grooved; the surface 

 of the valves is either smooth or sulcate. Eleven species are 

 known, chiefly from Senegal, India, Japan, and Australia. 



Species of Sunelta. 



Birmanica, Phil. seminuda, Phil. 



effossa, Hanley, Solaudri, Gray. 



excavata, Hanley. subquadrata, Sow. 



menstrualis, Mice. truncata, Desh. 



Meroe, Linn. vaginalis, Mke. 

 scripta, Linn. 



Genus CIRCE, Schumacher. 



Shell ovate, or sub- trigonal, often lentiform, beaks de- 

 pressed ; margins of valves entire, or sometimes crenulated. 

 Hinge tri-dentate ; teeth unequal, diverging, lunular tooth 

 compressed, separate from the hinge-margin. Pallial im- 

 pression simple. 



Ex. C. scripta, Linmeus, pi. 108, fig. 4, 4, a. 



In the genus Circe the shell is more or less triangular, 

 solid, equivalve, and closed ; the surface of the valves is 

 smooth, or concentrically striated or grooved ; the beaks 

 are often curiously depressed, and not very prominent ; and 



