136 CO'^CEYLIA—DITHYRA. 35. 



is chalky white, rounded, a little sloping and produced on the car- 

 tilage side, finely striate transversely : beaks pointed, curving to one 

 side, without any impression under them : inside chalky white but 

 not glossy, with the margin plain and very sharp edgtd. 



triangularis. Cypkina testd subtrigond Icevi, areola posticd lunceolatd, valvd allerd 

 tridentatd. 

 Shell somewhat triangular smooth, with the hinder impression lan- 

 ceolate, and three teeth in one of the valves. 

 Tabnost. 11, fig. 19,20. 

 Venus triangularis. Montagu, p. 577, tab. 17, fig. 3. 

 Linn. Trann. yVu. p. S3. 

 Turton, British Fauna, p. 160. 

 Pennant, Brit. Zool. iv. p. 205. 

 Dillwyn, Descript. Catal. p. 173. 

 Turton, Couch. Diet. p. 238. 

 Muf. nost. Western coasts, and Dublin bay. 



Shell about half an inch in diameter, strong, roundish with a tri- 

 angular outline towards the beaks which are produced and equally 

 sloping on both sides ; the surface smooth, or marked with a few 

 transverse lines of annotination : in one valve two teeth and a curv- 

 ed lateral one; in the other three teeth and a lateral one. 



compressa. Cyprina testd trigono-orhiculari subcompressd, costulis transversis re- 

 motiusculis, areola posticd elongatd, dentibus dxiobus. 



