432 dosiniinjE. 



polita, Desh. Sieboldii, Reeve. 



pondei'osa, Gray. simplex, Hartley. 



prostrata, Linn. solidula, Sow. 



pubescens, Phil. striatissima, Sow. 



radiata, Reeve. subrosea, Gray. 



reticulata, Recluz. subtrigona, Sow. 



rubicunda, Phil. tenuilamellata, Sow. 



scabra, Phil. torrida, Reeve. 



scabriuscula, Phil. Traillii, A. Adams. 



scalaris, Mice. tumida, Gray. 



sculpta, Hanley. turgida, Reeve. 



serniobliterata, Desh. variegata, Chem. 

 sericea, Reeve. 



Genus CYCLINA, Deshayes. 



Animal like that of Dosinia. 



Shell circular, thin, inflated, inequilateral, transversely 

 striated, and with no lunular area; beaks small, approxi- 

 mated; margins simple, or sometimes crenulated. Hinge 

 wide, flat, tri-dentate in one valve and bi-dentate in the 

 other ; ligament external, somewhat covered by the margin 

 of the rirna. Muscular impression posterior, remote from 

 the cardinal margin ; sinus of pallial impression triangular, 

 oblique, often ascending. 



Ex. C. Chinensis, Chemnitz, pi. 108, fig. 6, 6, a. 



In Cyclina the orifice of the branchial siphon is fringed, 

 and that of the anal is simple. The shell is thin, and more 

 or less orbicular, with the inner margins of the valves cre- 

 nulated ; the pallial sinus is wide, deep, central, and obtuse ; 

 the hinge is composed of two diverging primary teeth (one 

 of which is bifid) in the right valve, and three (the central 

 one bifid) in the left ; the ligament is external and promi- 

 nent ; and there is no distinct lunule. The few species 

 described are from China and India. 



