122 



A. SQUAMULA.ZW. 1161.? Mont. p. 156 fy 561. 

 Dor. Cat. t. 13./.J4. 2W*.D. p. 3. F. p. 395. 

 Turt. B.p. 229. . 18./. 5,6,7. Somewhat orbicular, 

 smooth, transparent, flat or a little tumid about the 

 beaks, thin, brittle ; operculum tendinous, seldom hard 

 at the base, with a testaceous termination, i. Common 

 on old shells. 



A. UNDULATA. Gmel. 3346. Mont. p. 157. t. 4. 

 /. 6. Pen. 4. p. 233. Dor. Cat. p. 39. t. 11. /. 4. 

 D.^. 289. Turt. D.p. 4.F. ^. 395. 7. 5. 

 #. 10. /. 8,9,10. OSTREA STRIATA. Mont. p. 153. 

 and Supp. 580. Don. t. 45. Rounded or oblong, 

 very variable in figure, sometimes very convex and 

 opaque, often thin, transparent and flat; upper valve 

 furnished with numerous radiating striae which cause the 

 margin to be crenated ; inside rich green with an irre- 

 descent blue border ; perforation large, on one side of 

 it a triangular striated cavity ; the plug terminating in a 

 thin oval layer, strongly striated transversely and crossed 

 by fine longitudinal lines. 1. On old shells and cre- 

 vices of rocks. 



A. PUNCTATA. Turt. B. p. 232. t. 18. /. 11. F. 

 p. 395. Orbicular, thin, transparent, purplish white, 

 a little truncated at the base ; upper valve convex and 



