26 TESTACEOUS MOLLUSCA. 



Section Tenuipedes. 



The mantle barely united before ; foot small, and compressed ; 

 shell having but a moderate gape. 



TRIBE MACTRACEA. 



Equivalve shells, frequently gaping at the lateral extremities; 

 with 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 internal, attached to the cardinal pits. 



* Transversely oblong. 



L. Solenoides. Lam. l.—BL t. 77. f. 3.— Sow. G. f. 1.— 

 Mya Oblonga. Gm. 3221.— -Mactra Hyans. D. p. 146.— 

 Mont. p. 101.— Don. t. 140.— Ch.f. 12.— W. t. h.f. 37.- L. 

 Oblonga. Turt. B. p. 64. t. h.f. 6. Oblong, \he posterior 

 side short and "rounded, the anterior produced and obtuse, margins 

 nearly parallel, the dorsal slightly incurved ; yellowish-white or 

 rufous under a thick epidermis, with irregular rugged transverse 

 striae ; hinge with a grooved, flattish, tooth, locking between two 

 others in the opposite valve. 2\. — Europe. 



L. Elliptica. Lam. 2. —Turt. B. p. 65. — Mactra Lutra- 

 ria. Lin. G'mel. 3259.— W. t. 6.f. 36.— Mont. p. 99.— JD. p. 145. 

 — List. t. 415. /. 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.. 3^. — Europe. 



L. Rugosa. Lam. 3. — Mactra Rugosa. Gmel. 3261. — D. 

 p. 145.— Ch. f 236. 7.—E. t. 254. /. 2.— W. t. 6. f 33. 

 Transversely ovate, yellowish-white, marked with strong longitudinal 

 and obsolete transverse striae, except at the extremities which are 

 smooth and somewhat glabrous. — Europe. 



L. Egyptiaca. Gray.— Mact. E. D. p. 145.— Ch. f 1955, 

 6. — W. t. 6. /. 34. Oblong-oval, obtuse at the extremities, ven- 

 tral margin little curved ; white under a yellowish epidermis, longi- 

 tudinally striated. 1 . .£ . — Red Sea. 



L. Elongata. — Gray. Mag. Nat. 1837. Elongated, ovate- 



