122 
A. Squamuta. Lin. 1151.?—Mont. p. 156 §& 561. | 
—Dor. Cat. t.13. f24.—Turt.D. p. 3.—F. p. 395.— 
Turt. B. p. 229. t. 18. f. 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. %. Common 
on old shells. 
A. Unputata. Gmel. 3346.—Mont. p. 157. ¢. 4. 
f. 6.—Pen. 4: p. 233.—Dor. Cat. p. 39. t. 11. f. 4. 
—D. p. 289.—Turt. D. p. 4.—F. p. 395.—Turt. B. 
t. 10. f. 8,9,10.—OstrEA Srriata. Mont. p. 153. 
and Supp. 580.—Don. ¢. 45.—Rounded or oblong, 
very variable in figure, sometimes very convex and 
opaque, often thin, transparent and flat; upper valve 
furnished with numerous radiating strize 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. f. 11.—F. 
p. 395.—Orbicular, thin, transparent, purplish white, 
a little truncated at the base; upper valve convex and 
