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TESTACEOUS MOLLUSCA. 
I’, Crocra Lam. 4.—List. t. 253. f.190.—Ch. f. 496.—E. t. 
235. f-2. Oval, longitudinally striated, somewhat saffron coloured, 
particularly towards the margin, ribs narrow imbricated and scaly ; 
scales numerous and most of them short but slightly raised at the 
margin, posterior depression large.-—Var. (Cuama Gicas var. C. 
D. p. 214.—Gualt. t. 92. A.) Whitish.— 4. Indian Ocean...South 
Seas ? 
T. Murica Lam. 5.—Ast. t. 80. f. 1,2,3. Large, oval, ven- 
tricose, ribs smooth but becoming scaly towards the margin, scales 
depressed, interstices of the ribs longitudinally striated, posterior 
aperture small, and the inner margin scarcely crenulated.—145. . 
Indian Ocean. 
T. SerriFERA. Lam. 6.—Cuama Gieas var. D. D. p. 214.— 
Ch. f. 497.—E. t. 235. f. 8. Oval, ventricose, uniform white, the 
ribs longitudinally striated and unarmed, except the extreme pos- 
terior ones which have scales resembling the teeth of a saw: inter- 
stices with strong longitudinal grooves, the ventral margin very 
rounded, posterior gape very small. 43..6. Indian Ocean. A 
Sew small scales are sometimes seen on the ‘anter vor extremity. 
HIPPOPUS. 
Equivalve, regular, inequilateral and transverse ; lunule not gaping ; 
hinge mith two compressed unequal anterior inserted teeth; lhga- 
ment marginal and external. 
H.Macuratus. Lam. 1. —Sow. G.— Reeve. t. 98. f. 1.—Cua- 
MA Hipporus. Lin. 1137. ay p. 215.—Ch. f. 498, 9.—W. t. 9. 
f-2.—D. t. 236. f. 2. Transversely ovate, thick, heavy and ven- 
tricose, white or yellowish with scattered purplish red spots ; some- 
what scaly, ribbed ; posterior depression heart-shaped and oblique 
Indian Ocean. 6. 
TRIBE MYTILACEA., 
Hinge nith a subnternal marginal ligament, which is linear, very en- 
tire, and occupies a considerable portion of the anterior margin ; 
shell rarely foliaceous. 
MODIOLA. 
Subtransverse, equvalve, regular ; the posterior side very short ; beaks 
nearly lateral and inclined to the shorter side ; hinge jai teeth, 
lateral and linear ; ligament placed in a marginal furrow, and 
nearly internal ; a muscular unpression which is sublateral, elon- 
gated and hatchet-shaped. 
