164 MYADiE. 



vi. p. ij, pi. 1, f, 1, 2. — Spengl. Skrivt. Naturli. Selskab. vol. 

 iii. part 1, p. 28. — Wood, General Conch, p. 90, pi. 17, f. 1, 



2. — DiLLW. Recent Shells, p. 42 Lam. Anim. s. Vert. ed. 2, 



vol. vi. p. 73. — Burrows, Conch, pi. 4, f. 1, 2. — Ind. Testae, 

 pi. 2, Mya f. 2.— Crouch, Introd. Conch, pi. 3,f. 6, 7.— Sow. 

 Conch. Manual, f. 71. — Desh. Elem. Conch, pi. 8, f. 2. — 

 Hanl. Recent Shells, p. 19, pi. 2, Mya f. 2.— Gould, Invert. 

 Massac, p. 42. — Dekav, New York Mollusc, p. 240, pi. 29, 

 f. 289. 



C/iivna inincat(i,DA Costa, Brit. Conch, p. 233, pi. 16, f. 1. 



Mya ovalis, (immature.) Turt. Ditliy. Brit. p. 33, pi. 3, f. 1, 2. 



Spluema Swai/isoni, (fry.) Turt. Ditliy. Brit. p. 37, pi. 19, f. 2. — Flem. Brit. 

 Anim. p. 466. — Brit. Marine Conch, p. 57. 



Mi/e tronqiiic, Chenu, Traite Elem. p. 48, f. 152. 



Ency. Meth. Vers. pi. 229, f. 2. 



This ancient and well-known shell is of a sub-oval form, 

 which is at times produced, but more generally abbre- 

 viated, subequilateral, more or less solid, opaque, and ven- 

 tricose. This latter characteristic is, however, 'chiefly 

 manifested towards the rounded end, there being a con- 

 siderable degree of flattening of the central surface, which, 

 after a slight retusion, again swells out at the truncated 

 tips of the posterior extremity, of which latter the hiatus is 

 extremely large, more or less oval in shape, and not ex- 

 tending below beyond the ventral margin ; the lips of this 

 gape are reflexed, and there is not any tendency to stric- 

 ture. A loose, yellowish-grey epidermis (which is con- 

 tinued posteriorly beyond the shell to the animal,) covers 

 the entire valves, which beneath it are of a more or less 

 squalid dull uniform white, and concentrically traversed by 

 irregular but very distinct wrinkles, which are often almost 

 pliciform at the sides, where they are always most deve- 

 loped. The dorsal and ventral margins are almost parallel; 

 the latter is more or less straight, a little retuse at or be- 

 hind the middle, more convex in front, and more ascending 

 posteriorly. The former, immediately adjacent to the um- 

 bones, is subretuse in front, and not at all declining ; but. 



