ODOSTOMIA. 297 



raised lines on the lower part of the body, that run in a 

 line with the upper extremity of the aperture ; more rarely 

 they both of them are continued upon the penult turn. 

 The spire is composed of five tapering volutions, which are 

 a little convex, of slow longitudinal increase, moderately 

 elevated, and not scalar, but rather abruptly inclining 

 inwards at their bases. The apex is blunt. The body, 

 whose basal declination is abruptly rounded, is generally 

 rather flattish posteriorly. The mouth occupies nearly 

 one-third of the total length, and is of a subrhomboid oval 

 figure, the scarcely convex base of the preceding turn 

 forming an angle with the columella ; the posterior con- 

 traction is rather sudden. The acute and simple outer 

 lip, which is straightish or only slightly convex above, 

 arches or rather slants in more or less abruptly anteriorly, 

 and forms an angle with the pillar lip. This last, which is 

 straightish or but slightly curved, is peculiar in being 

 broadly erect, folding back slightly, however, near the 

 base: it is flanked by a more or less perceptible umbilical 

 chink. The tooth-like fold is tolerably large, and nearly 

 horizontal ; it lies only a little above the middle of the 

 inner lip, but so retired, that it is scarcely apparent in 

 unworn individuals. The ordinary length of full-grown 

 examples is the eighth of an inch ; this is nearly thrice 

 their basal diameter. 



" Animal white throughout. Mantle fleshy, protrud- 

 ing a little beyond the margin of the aperture. Head, a 

 narrow cloven muzzle, issuing between the foot and under 

 the coalescing tentacular membrane. The tentacula are 

 exceedingly short, strong, rather flat, setose, very obtusely 

 pointed. The eyes are distinct, and immersed in the skin 

 of their internal bases. The foot is very small and short, 

 scarcely extending beyond the basal volution, truncate in 



VOL. III. Q u 



