ae) 
S. Novacuna. Mont. p. 47.—Dirt. B. p. 80. 
F. p. 459.—A single strong, curved, blunt tooth in each 
valve; shell destitute of the terminal stricture. 4. 
Nearly resembling the following but differing by the 
number of its teeth and the absence of the lateral ones. 
S. Srrrqua. Lin. 1113.—D. p. 58.—Lam. 4.—Ch. 
29.—Don. t. 46.—Pen. 4. p. 83. t. 45. f. 20.— 
Mont. p. 46.—Turt. B. p. 80.—F. 459.—Swaight, 
with an olive brown cuticle which is darkest posteriorly ; 
a single tooth and a remote lateral lamina in one valve, 
in the other, are two besides a lateral inclined tooth 
corresponding with the opposite lamina.  1...7, 
Common. 
S. Ensis. Lin. 1114.—D. p. 59.—Lam. 5.—Ch. f. 
29, 30.—Don. t.50.—Pen. 4. p. 83.—Mont. p. 48— 
Turt. B. p, 82.—F. p. 459.—Linear, slightly curved, 
the cuticle olive brown, both the ends somewhat 
rounded ; two teeth in one valve, one in the other, one 
of the lateral teeth grooved ; hinge not terminal; pos- 
teriorly rounded. %...6. Common. 
* * Hinge not terminal ; posteriorly rounded. 
S. Pettucipus. Pen. 4. t.46. f. 22,—Mont. p. 49. 
—Turt.B, p. 83.—D. p.60,—F.p,549.—S, Premaus. 
