ODOSTOMIA. 291 



0. oHLiQUA, Alder. 



Body equal in length to the spire ; whorls convex, quite 

 smooth, of rapid longitudinal increase : no umbilicus : no fold. 



Plate XC VI.. fig. 1. 



Odosiomia obliqua. Alder (not Jeffreys), Ann. Nat. Hist. vol. xiii. p. 327, pi. 

 8, f. 1 2. 

 „ diapliuiui, Jeffrevs, Ann. Nat. Hist, new ser. vol. ii. p. 341, 

 young. 



This extremely rare shell somewhat reminds one of the 

 Bissoa vitrea, and like it lies on the confines of its genus. 

 The Warrenii seems to be its nearest congener, and, except 

 in sculpture, comes very close to it, so much so, indeed, 

 that the localities usually ascribed to the latter belong more 

 appropriately to the former species. It has an acuminated 

 oblong figure, is thin, semitransparent, a little glossy, quite 

 smooth, and of an uniform squalid white. There are only 

 five volutions, which are of very rapid longitudinal increase 

 (so that the penult turn, when viewed dorsally, is decidedly 

 high), and are deeply divided by an oblique and simple 

 suture : they are usually more rounded and perpendicular 

 below, more shelving and merely convex above ; those of 

 the spire are subventricose and quickly tapering ; the 

 apical nucleus is moderately pointed and somewhat twisted 

 aside. The body, which is fully equal to the spire in 

 length, and often, indeed, exceeds it, is narrow, broadly 

 rounded at the periphery, and convex in the declination of 

 its very gradually attenuated anterior extremity. The 

 narrow aperture, which is about equal to the spire in 

 length, is oblong-ovate, and gradually contracted poste- 

 riorly by the moderately convex swell of the base of the 

 preceding whorl. The outer lip is simple, very acute. 



