230 CONCHYLIA— D/THYi?^. 50. 



In all its stages of growth this species may be readily distin- 

 guished from any of the varieties of Anomia Ephippium. It is 

 usually fiat, sometimes a little tumid about the beaks, nearly orbic- 

 ular, without wrinkles or undulations, and of a whitish or corneous 

 color. The usual diameter is from a quarter to half an inch, but we 

 have met with it nearly two inches. The base is occasionally trun- 

 cate, as often happens to the younger ones of Anomia Ephippium 

 and A. undulata. The substance is always thin and brittle ; and the 

 plug of attachment is tendinous, seldom hard at the base, with a 

 testaceous termination. 



Large specimens sometimes cover the part near the hinge of the 

 Pecten opercularis, partaking of the convexity, ribs, and strioe of its 

 foster parent. 



undulata. Anomia testd rotundatd seu oblongd, striis longitudinalihus undulatis, 

 valvd inferiori fovea trigond sub umbonem. 

 Shell rounded or oblong, with longitudinal undulate striae, and a 

 triangular cavity on the under valve beneath the hinge. 



Tab. nost. 18, fig. 8, 9, 10. 

 Anomia undulata. Gmelin, Syst. p. 3346. 



Turton, Linn. Syst. iv. p. 286. 



Chemnitz, viii. p. 88, tab. 77, fig. 699. 



Montagu, p. 157, tab. 4, fig. 6. 



Pennant, Brit. Zool. iv. 233. 



Turton, British Fauna, p. 163. 



Dorset Catal. p. 39, tab. 11, fig. 4. 



Dillwyn, Descript. Catal. p. 289. 



Turton, Conch. Diet. p. 4. 

 O.strea striata. Da Costa, p. 162, tab. 11, fig. 4. 



