480 FISSURELLID.E. 



The beautiful rosy hue of the aperture, from which 

 this species has derived its name, must, we fear, be con- 

 sidered exceptional, rather than otherwise, since, in the 

 majority of individuals, the shell is of a squalid white 

 both within and without. Its shape is more or less 

 conical, but with the front dorsal outline very strongly 

 arched, and the vertex greatly recurved, so that a line 

 dropped from the most projecting posterior portion of it 

 would fall beyond the basal margin. The sides of the 

 shell, which is tolerably strong for its size, devoid of 

 lustre, and nearly opaque, are somewhat compressed ; the 

 base is oval or rounded oval, slightly or but moderately 

 convex at the sides, arched at both extremities, and a 

 little reflected posteriorly. Behind the vertex, which is 

 hooked and subspiral, the outline is much incurved, and 

 the declination is very abrupt. The marginal slit is 

 narrow, and of equal breadth throughout ; although nearly 

 as high as in the preceding species, it is much shorter in 

 proportion to the distance from its termination to the 

 extreme point of the vertex. The sculpture, at first sight, 

 bears much resemblance (especially in worn specimens) 

 to that of reticulata, but in characteristic and uninjured 

 examples, the longitudinal ribs are distinctly seen to be 

 closer set, larger in proportion to the interstitial spaces, 

 and subgranose, or rather subgeniculated, the concentric 

 lines to be less prominent and very oblique, and the pro- 

 found hollows to be on a smaller scale. The ordinary 

 length is not above the fifth of an inch. 



Animal white. The head projects immediately in front 

 of the fissure in the shell, and is rather short and small, 

 with an oblong muzzle ; the tentacula are rather long, but 

 stout ; at their external bases are distinct but short pedi- 

 cles, bearing rather large eyes. The mantle does not 



