230 CO'SCUYLlk— D J THYR A. 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 

 orbicular, 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 truncate, 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 

 striae of its foster parent. 



iindijlata. Anomia testd roUmdatd seu oblongd, striis longiiudinalUms 

 undulatis, valvd inferiori foved 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. 



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



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



Pennant, Brit. Zool. iv. 2.33. 



Turton, British Fauna, p. 163. 



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



DiUwyn, Descript. Catal. p. 289. 



Turton, Conch. Diet. p. 4. 

 Ostrea striata. Da Costa, p. 162, tab. 11, fig. 4. 



