CONCHYLIA— l>Jr//r/e.4. .50. 231 



Mnnlagu, Test. p. 1.5.3, and Suppl. p. 580. 



Donovan, British Shells, ii. tab. 45. 

 Ostrea subviridis. Lister, Conch, tab. 202, fi^. .36. 

 Miis. most. On old shells, and the crevices of rocks. 



Shell an inch or more in diameter, very variable in figure and 

 consistence, sometimes very convex and opake, ofteu thin trans- 

 parent and tiat; sometimes the under valve is more convex than 

 the upper, which is rarely concave; but always furnished with 

 numerous radiating stria; which cause the margin to be crenate : 

 inside of a rich and splendid green, with an iridescent blue 

 margin : the beak is generally terminal, but in the flatter varieties 

 not quite so : the perforation is large, and sometimes quite entire. 



On the under valve, on one side of the perforation, is a trian- 

 gular striated cavity, resembling that which is seen on the valves 

 of the Pecten, as if it had contained an additional ligament for 

 the more safe attachment. 



The plug terminates in a thin oval layer, strongly striate trans- 

 versely, and crossed with fine longitudinal lines, frequently found 

 on the valves of the Pinna ingens. 



The varieties figured at 12 and 13, we have taken from the 

 cavities of rocks in Torbay. They are extremely thin and 

 brittle, resembling brown paper: the upper valve a little concave, 

 and clothed with thin greenish-white scales ; the under valve 

 very convex and fragile: the longitudinal striae very obscure. 



Anomia testa obicnlari, vahd superiori punctis elevatis, infe- punctafa. 



riori punctis concavis. 

 Shell orbicular, with raised dots on the upper valve and concave 



ones on the under valve. 



