26 TESTACEOUS MOLLUSCA. 
Section TENUIPEDES. 
The mantle barely united before ; foot small, and compressed ; 
shell having but a moderate gape. 
TRIBE MACTRACEA. 
Hquivalve shells, frequently gaping at the lateral extremities ; 
mith an internal ligament, or partly external, and the animal 
having a small compressed foot. 
LUTRARIA. 
Inequilateral, transversely oblong, or rounded, gaping at the ex- 
tremities ; hinge with one tooth, which is somewhat complicated, 
or two teeth, of which one is simple, with an adjoining deltoid 
hollow, which is oblique, and prominent within; no lateral 
teeth ; ligament internat, attached to the cardinal pits. 
* Transversely oblong. 
L. Sorenorwes. Lam. 1.—Bl. t. 77. f. 3.—Som. G. f. 1.— 
Mya Ostonea. Gm. 3221.—Macrra Hyans. D. p. 146.— 
Mont. p. 101.—Don. t. 140.—Ch.f. 12.—W. ¢. 16. f. 37.—L. 
Ostonea. Turt. B. p. 64. t. 5.f. 6. Oblong, the posterior 
side short and rounded, the anterior produced and obtuse, margins 
nearly parallel, the dorsal slightly meurved ; yellowish-white or 
rufous under a thick epidermis, with irregular rugged transverse 
strie ; hinge with a grooved, flattish, tooth, locking between two 
others in the opposite valve. 24.—Hurope. 
L. Evurprica. Lam. 2.—Turt. B. p. 65.—Mactra Lutra- 
ria. Lin. Gmel.3259.—W. t. 6. f. 36.— Mont. p. 99.—D. p. 145. 
—FTist. t. 415. f. 259.—Ch. f. 240, 1—Don. 2. t. 58. Oblong, 
nearly equivalve, marked only with the lines of growth and remote 
obsolete ridges, anterior side the longer, rounded and slightly 
gaping at both ends, yellowish white under a thin close cuticle. 
2..31.— Europe. 
L. Rucosa. Lam. 3.—Macrra Rucosa. Gimel. 3261.—D. 
p. 145.—Ch. f. 236. 7.—H. t. 254. f. 2.—W. t. 6. f. 33. 
Transversely ovate, yellowish-white, marked with strong longitudinal 
and obsolete transverse strize, except at the extremities which are 
smooth and somewhat glabrous.— wrope. 
L. Eeypriaca. Gray.—Macr. E. D. p. 145.—Ch. f. 1955, 
6.—W. t. 6. f. 34. Oblong-oval, obtuse at the extremities, ven- 
tral margin little curved; white under a yellowish epidermis, longi- 
tudinally striated. 1..2.—Red Sea. 
L. Evroneata.— Gray. Mag. Nat. 1837. Hlongated, ovate- 
