12 TESTACEOUS MOLLUSCA. 



Bon. t. 50.— W. t. 3./. 6.— List. t. AW.— Mont. p. 48.— Turt. 

 B. p. 82. Linear, slightly curved, brittle, cuticle olive brown : 

 binge with two teeth in one valve and one in the other, with one of 

 the lateral teeth grooved ... up to 6. — Europe. 



S. Viridis. Say, Jour. A. N. S. Phil. 2. p. 316. Fragile, 

 elongated, compressed, posteriorly obliquely truncated, a little re- 

 flected and rounded near the base, anteriorly rounded and a little 

 narrowed ; cuticle pale green, slightly wrinkled concentrically, the 

 wrinkles regularly rounded towards the extremity, dorsal edge nearly 

 straight, ventral slightly curved ; in each valve a tooth having a flat- 

 tened vertical surface, which turns upon that of the opposite tooth. 



S. Linearis. Chem.—B. p. 59.— Wood. G. C. p. 121. t. 

 27.f.3.—Ch.f. 1931, 2.— IF. t. 3./. 6. Linear, straight, nar- 

 row, sub-cylindrical, very thin, pale purplish rose colour : hinge 

 with a single tooth in each valve. J . . 3. — Nicobar Isles. 



S. Scalprum. King in Z.J. 5. Linear, sub-arcuated, fragile, 

 rather broader and rounded anteriorly, posterior edge convex ; 

 entirely covered by a pea-green epidermis under which it is uniform 

 white : inside white, hinge terminal, one valve with a double tooth 

 resembling the sprouting horns of a heifer, besides an obtuse denticle, 

 two distant and a rudimentary one in the other, f . . 2f . — Patagonia. 



S. Sloanii. Gray in Brit. Mus. Linear, straight, narrow, 

 fragile, pellucid, rather broader and obtusely rounded anteriorly, 

 truncated posteriorly : under a yellowish olive epidermis, white 

 spotted with tawny brown : a sharp prominent tooth in one valve, 

 the vestiges of one in the other. \ ..3. 



S. Truncatus. Wood G. C. t. 26. f. S.—B. p. 58.— Sow. G. 

 f. I.— Reeve, t. 25. f. l.—Knorr. 1. t. 28./. 3.—W. t. 3. /. 

 4. — S. Ceylanensis, Leach in Z. M. 1. t. 7 Linear, straight, 

 breadth not more than quadruple the length, margins parallel the 

 whole way, truncated at both ends, posteriorly the edge convex, 

 anteriorly slightly concave and with the slightest border; the con- 

 centric bands purplish crimson : hinge with a single opposite tooth 

 in each valve. \\ . .5. — Ceylon, fyc. 



S. Guinensis. Gray in Brit. Mus. Linear, straight, breadth 

 but little more than quadruple the length, margins sub-parallel, 

 truncated at both ends, anteriorly sub-directly so, posteriorly 

 obliquely and with a slight hollow near the edge : under an olive- 

 fulvous epidermis, white with purple madder lines of growth : hinge 

 in each valve a single large stout tooth, having the surface at the 

 point of contact perpendicularly flattened, semicircular and mar- 

 gined. . . 2^. 



S. Brevis. Gray in Brit. Mus. — S. Truncatus, var. 

 Wood. G. C. t. 27. f. 2.—B. p. 58. -Fav. t. 55. B. 1.— S. 

 Truncatus. Mawe. t. o.f. 2. Linear, straight, broad, margins 



