46 LITTORINIDJ?. 



Litlorina obtusuta, Menke, Zeitsch. Mai. 1845, p. 55. — Lov^N, Index Moll- 

 Scandinav. p. 22. — Philippi, Neue Conch, vol. ii. p. 104. 

 Litt. pi. 1, f. 20, 21, 22. — MiDDEND. Malae.Rossic. pt. 2, 

 3, p. 57, pi. viii, f. 24—28. 



Of this very common shell there are two marked varia- 

 tions in shape, besides subordinate ones. We j^ropose to 

 describe the more typical of these first, and then to indi- 

 cate the peculiarities of the other variety. This form has 

 a transversely, and generally obliquely, oval contour, is 

 opaque, very solid, more or less dull, and of various 

 shades of yellow, rufous, or brown, either uniform, or 

 banded with the first on a ground of either of the two 

 darker colours, or vice versa. Oftentimes, too, it is re- 

 ticulated by closely-disposed zig-zag lines, that radiate 

 at first from the sutures in simple curves. The surface 

 is nearly smooth under its epidermis, being only, at most, 

 very finely and densely striolate in a spiral direction. The 

 spire is remarkably depressed, and composed of about 

 three-and-a-half turns, that at first slowly, and then quickly 

 enlarge, and commence from a blunt yet very small apex : 

 they are scarcely raised, very gently shelving, flattened 

 above, more convex below, and separated from each 

 other by a very fine suture, over which the succeeding 

 whorl is wont to lap. The great disparity in length 

 between the dorsal and ventral surfaces of the penult 

 turn is very characteristic of the species. The body 

 is ample, placed obliquely with respect to the other 

 volutions (so that the spire is lateral), and usually 

 produced at the anterior base in full-grown examples ; 

 it is bluntly subangulated above, gently shelving and 

 a little flattened below, and plano-convex in the middle, 

 hence the circumference opposite the mouth, instead 

 of being I'ounded, as in most Littorlna; is broadly and 

 slightly convex. The aperture which is rounded oval, 



