46 
tooth in each valve, and an adjacent heart-shaped 
cavity, two lateral compressed teeth situated near 
the hinge and inserted; ligament internal and 
placed in the wit of the hinge. 
* Lateral teeth striated. 
M. Souipa. Lin. 1126.—D. p. 140.—Lam. 23.— 
Pen. 4. p. 123. t: 55. f.2.—Ch. f. 229, 230.—Don. 
t. 61.—Mont. p. 92.— Lin. T. 8. p. 70.—Dor. Cat. p. 
32. t. 6. f.6.—Turt. C. D. p. 81.—Da. Cos. t. 14. 
jf. 6.—Sub-triangular, strong, opaque, sub-equilateral , 
slightly depressed from the beaks at both extremities, 
nearly smooth, with a few concentric antiquated ridges, 
dull dirty white; inside glossy and white. 12...14. 
Common. 
M: Truncata. Mont. Sup. p.34.—Turt B. p. 68. 
—F. p. 427.—M. Sustruncata. Don. t. 126.— 
M. CrassaTELLA. Lam. 33.—Triangular, equilateral, 
solid, depressed from the beaks at both extremities, so 
that the sides almost form a rectangle at the prominent 
beaks; convex, solid, opaque, dull yellowish white, 
sub-angulated anteriorly, irregularly striated by the 
lines of growth: umbones large and prominent, slopes 
striated. 13...13. Teignmouth and Scotland. 
