fil 



the interstices ; anterior end mostly gaping,rarely some- 

 what closed ; inside white with frequently a chocolate 

 blotch at one end, margin entire, hinge suhterminal. 

 | ... |. Torbay, in Rocks. 



V. PERFORANS. Lam. \.-^Turt. B. p. 29. t. 2. / 

 15 to 18. P.p. 451. VENUS P. Mont. p. 127. t. 3, 

 / 6. Lin. T. 8, p. S9.Pen. 4. p. 1 1 1. D. p. 206. 

 - Turt. C. D. p< 245, Variable in shape, more or less 

 oblong, angularly truncated at one end (sometimes 

 rounded at both ends or kidney-shaped and indented) 

 very inequilateral, with transverse striae which become 

 lamellar anteriorly, and minute radiating ones; brownish 

 or yellowish white, with sometimes a few purple 

 broken rays and linear ziczacs; inside white, glossy, 

 with mostly a purple blotch at the larger end, margin 

 entire ; hinge with three erect, long, and somewhat re- 

 curved teeth in each valve, two of them cloven, the 

 lower one in the right valve and the upper one in the 

 left, entire and much the smaller. 1...2?. In rocks, 

 common. The young are compressed, white variously 

 marked with purple blotches anteriorly. 



TRIEE. NYMPHACEA. 



Never having more than two cardinal teeth in the same 

 valve, often gaping at the lateral extremities ; liga- 

 went external, umbones muaify projecting outwards. 



