51 
valve, and a concave tooth and remote lateral one wn 
the other : ligament internal. 
K. SusorBictuaRis. Turt. B. p. 57. €. (1. f. 5,6 
—F. p. 430 --Mya. S. J.ont. p. 39. and 564. t. 26. 
f. 6.—Lin. T. 8.p.41.—Wood. G.C.p. \11.—D. p. 
55.—Sub-orbicular, equilateral, very convex, yel- 
lowish white, with slight concentric striz; ventral 
edge nearly straight, ends rounded ; cuticle thin, green- 
ish, prismatic. +. Roots of sea-weed. 
K. Rusra. Turt. B p.58. t. LL. £7, 8.—F. p. 
430.—Carpium R. Mont, p. *3. t. 27. f. 4.—Wood. 
G. C. p. 213.—D. p. 1381.—Walk. t. 3. f. 86.—Oval, 
inequilateral, reddish and very finely shagreened (often 
paler or covered with a rough green or brown coat; 
beaks prominent, subterminal, under which the margin 
slopes in an incurved manner towards the smaller end: 
inside glossy purple. 0,80...0,10. Roots of sea-weed. 
Grnus.—MONTACUTA. Turton. 
Oval or oblong, equivalve, inequilateral, mostly closed ; 
hinge with two teeth in each valve and a cavity 
between them; lateral teeth none: ligament i- 
ternal. 
M.Susstruata. Turt. B. p. 59. t. 11. f.9. 10. 
—F. p, 465.—Licura S. Mont. sup. p. 25.—Mva 
c 2, 
