12 TESTACEOUS MOLLUSCA. 
Don. t. 50.—W. t. 3. f. 6.— List. t. 411.— Mont. p. 48.— Turt. 
B.p. 82. Linear, slightly curved, brittle, cuticle olive brown : 
hinge with two teeth in one valve and one in the other, with one of 
the lateral teeth grooved ...up to 6.—urope. 
S. Viripis. 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- 
He vertical surface, which turns upon that of the opposite tooth. 
y+ 235-—U. States. 
S. Linzaris. Chem.—D. p- 59.—Wood. G. C. p. 121. t. 
27. f.3.—Ch. f. 1931, 2. —W.t. 3.f.6. Linear, straight, nar- 
row, sub-cylindrical, very thin, pale purplish rose colour: hinge 
with a single toothin each valve. 3..3.— Nicobar Isles. 
S. Scarprum. 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. 2..23.— Patagonia. 
S.Sroann. 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. 5..3. 
S. Truncatus. WoodG. C.t. 26. f.3.—D. p. 58.—Son. G. 
f. \—Reeve. t..25. f. 1.—Knorr. 1. t. 28. f. 3.—W. t. 3. f. 
4.—S. Ceyvtanensis, Leach in Z. M. ie 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. 13..5.—Ceylon, Se. 
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- 
S. Brevis. Gray in Brit. Mus.—S. Truncatus, var. 
Wood. G. C. t. 27. f. 2.—D. p. 58.—Fav. t. 55. B. 1.—S. 
Truncatus. Maye. t. 5. f-2. linear, straight, broad, margins 
