CO^CHYUli—DITHYRA. 11. 179 



Dorset Catal. tab. 1, fig. 16. 



Dillwyn, Descript. Catal. p. 245. 



Turton, Conch. Diet. p. 11, fig. 98. 



Chemnitz, x. p. 351, tab. 170, fig. 1657, 1658. 

 Area eaudata. Donovan, Britisli Shells, iii. tab. 78. 

 Area Modiolus. Walker, Minute Shells, p. 23, fig. 81. 

 Sandwich, Tenby, and Scotland. It is also abundant at Melville 

 Island, and in the polar seas. 



Sheila quarter of an inch long, and rather more broad, white 

 or yellowish, with a few ridges crossing the transverse striae: and 

 is distinguished from the last by the truncated smaller end, and 

 the angle of the marginal slope being not reticulate. 



41. CXRDIVM—LINNE. 



Testa subcordata, tequivalvis, costis plerumque longitudina' 

 libus ; umhonibus prominulis, contiguis. Cardo dentihus 

 duobus approximatis, obliquis, penetran(ibus ; lateralibus 

 utrinque remotis, insert is. Ligament um eaatermim. 



Shell somewhat heart-shaped, equivalve, mostly ribbed longitu- 

 dinally; with the beaks prominent and close together. Hinge 

 with two approximate penetrating teeth : and on each side 

 a remote lateral inserted tooth. Ligament external. 



2a 2 



