﻿328 



EOCENE MOLLUSCA. 



the spire, one of the transverse lines near the middle is more elevated than the 

 others, and the columella sometimes presents a third fold, much smaller than the 

 other two. In all other respects the shells from the two localities agree perfectly, 

 and the differences do not appear to me to be sufficient to justify their being considered 

 as specifically distinct. 



The shells which Rouault, in the first instance, separated under the specific name 

 Palemsis were subsequently ascertained by that author to be the adult shells of B. 

 Biaritzana, and were united by him to that species. 



Size. — Axis, 1 inch and 5-12ths; diameter, 7-12ths of an inch, nearly. 



Localities. — Bracklesham Bay and Bramshaw, at both of which places it is not 

 uncommon. French : Bos d'Arros. 



No. 250. Borsonia sulcata. F. E. Edwards. Tab. XXXIII, fig. 12, a, b. 



Borsonia sulcata. Morris, 1856. Forbes's Tert. fluvio-mar. Form., &c, p. 154, t. 5, 



fig. 3, 3 a, 3 b. 



B. testa ovato-fusiformi, semi-cosfatd, transversim sidcatd ; spird sub-turritd, acuminata : 

 anfractibus convexiuscidis ; marginibus poslices excavatis, ad suturam marginatis, caterum 

 lavibus ; costis crassiitsculis, rotundatis ; sulcis transversis sub-distaniibus, irregidaribus ■■ 

 aperturd oblongo-ovatd, in canali perbrevi, latissimo, exeunte ; labro arcuato , postice sinuato, 

 inius plicato ; sinu lato, paululum prof 'undo, rotundato .- columella oblique biplicatd, plicis 

 sub-aqualibus. 



A small, ovately fusiform shell, longitudinally ribbed and spirally furrowed ; the 

 spire, formed of from six to eight volutions, is moderately elevated, rather exceeding 

 the last whorl in length, and is somewhat turreted. The whorls are slightly convex ; a 

 deep, smooth furrow runs round the posterior margins, which are bordered round the 

 suture by an elevated, ridge-like line ; the last whorl is nearly conical, and terminates 

 in front in a short, but distinct, and very wide canal. The longitudinal ribs are rather 

 broad, very short, not extending beyond the middle of the whorls, and are lost on the 

 last whorl of the mature shell; the spiral furrows are wide, rather deep, concave, 

 somewhat distant, and separated by spaces wider than themselves, and rounded on 

 the upper surface. The aperture is of an oblong-ovate form ; the outer lip is mode- 

 rately arched, sharp on the edge, and plicated within ; and it presents, at the posterior 

 extremity, in the marginal furrow, a wide, but not very deep, rounded sinus ; and the 

 columella is slightly arched, and bears, about the middle, two nearly equal, moderately 

 oblique folds. 



In general aspect this species presents a strong resemblance to Borsonia (Pleuro- 

 iomd) nodularis (Desh.) ; but in that species the shell is wider and shorter, and the 

 surface is nearly smooth, except over the canal, which is traversed by a few concentric, 



