90 TESTACEOUS MOLLUSCA. 
equilateral, rather rhombic, compressed, thin, yellowish white, dia- 
phanous, umbones prominent, rather acute and tuberculose : liga- 
ment inconspicuous.—Variety—Orbicular, less compressed, sub- 
diaphanous and reddish brown.— Variety 2.—Orbicular, rhombie, 
rather ventricose, sub-diaphanous and reddish : umbones less pro- 
minent, blackish. 1..1.—dHurope. 
C. Osrusauis.* Lam. 6.—Del. t. 7. f. 2.—Pistp1um D. 
Pfeif. t. 5. f. 21, 2.—Gray. Turt. f. 149. Globose, obliquely 
sub-ovate, slightly inequilateral, shining, very finely striated, green- 
ish black, with a yellowish marginal zone, rarely altogether yellowish ; 
umbones rather prominent and very blunt.— Variety 1.—Ovate, 
triangular, very ventricose, blackish or ochraceous, edge very blunt. 
4.— Sweden, §¢. 
C. Fontinauis. Lam. 7. Drap.t. 10. f. 8. to 11.—Pusi1- 
La.* Turt. M.f.7.—Turt. B. p. 251. t. 11. f. 16, 7. Orbicular, 
ovate and rather compressed, very finely striated, and scarcely me- 
quilateral, umbones rather prominent. 1.—France, Sweden, &e. 
C. Ausrratis. Lam. 8. Somewhat heart- -shaped, tumid, 
opaque, inequilateral, with transverse groove-like Srna umbones 
prominent; beaks obliquely inclining.—Zimor. }.—Variety— 
Pellucid.—New Holland. 
G. Siminis. Say. in Nich. Enc. Amer. 4, t. 1. f. 9.—Gould. 
Mas. f. 53. p.73.—C. Suicata. Lam. 9.—Del. t. 7. f. 3. 
Sub-oval, sub-equilateral, marked with strongly raised lines of 
growth, very convex, the sides nearly equally rounded, the anterior 
slightly the larger and more pointed, the ventral edge very little 
arcuated, remarkably broad across the beaks, which are but slightly 
elevated, dark chesnut brown, inside bluish. The young thin and 
compressed, hinge with minute very oblique cardinal teeth, the late- 
ral distinct strong and white, the dorsal line nearly straight, and 
the extremities truncated, so as to Bre the shell a quadrilateral 
shape, light lemon or wax yellow. 4... 51,.—dJassachusets, North 
America. 
C. Srriatina. Lam. 10.—Del. t. 7. f. 4. Rounded, elliptic, 
somewhat inequilateral, posteriorly shorter and slightly angulated, 
greenish olive, convex, elegantly striated, beaks somewhat decorti- 
cated. 4.—Lake George in North America.—Smaller and more 
inequilateral than C. Cornea. 
C. Sarratroca. Lam. 11.— Del. t. 7. f. 9. Transversely 
oval, posteriorly rounded and rather shorter, with an obtuse anterior 
dorsal angle : a brownish epidermis and transverse striz : beaks 
decorticated and eroded. 1.—Sarratoga in North America. 
C. i ee N. Jenyns Monog. in Camb. Ph. 
SEE 16. 4. 20. f. 7,..8:—Gray.. Wurt. p. 283. f-, 150, 
Haase. el slightly inequilateral, very shining, finely striated, 
sides obtuse, ventral edge little arcuated, dorsal line scarcely slop- 
