﻿PROSOBRANCHIATA. 



325 



without the pullus, are slightly convex and bluntly angulated at the shoulders ; the pos- 

 terior margins are narrow, rather deeply channelled, very finely plicated round the 

 suture, and ornamented with several transverse raised lines, of which the one nearest the 

 edge is the most prominent ; the whorls in front of the shoulders are smooth ; the last 

 whorl tapers gradually towards the base, and is nearly conical, and over the front part 

 presents numerous transverse furrows, which become gradually obsolete as they mount 

 towards the middle of the whorl ; the anterior canal is wide, indistinct, and notched 

 at the extremity. The aperture is long, narrow, with straight, nearly parallel sides, 

 and, like that of P. amphieonus, resembles the aperture of a Cone ; the outer lip is 

 much expanded, approaching nearly to a semicircle in form, and is thin and sharp- 

 edged ; the columellar lip is thickened and produced in front ; the columella is nearly 

 cylindrical, and presents a prominent ridge or crest at the anterior extremity ; and 

 the sinus, which is placed in the margin of the whorl, is wide, but very shallow, re- 

 sembling in appearance that which characterises Bellardi's section, Pseudotomatce. 



I possess only one specimen of this Pleurotoma ; it has attained a larger size than 

 that attributed by Deshayes to the French shells, but the relative proportions are 

 the same in both. The transverse furrows over the base of the English shell are 

 coarser, and extend higher up the whorl than in the French shells, but in other 

 respects, and particularly in the narrow, concave, posterior margins of the whorls and 

 the peculiar character of the sinus, the two agree. 



Size. — Axis, 1 inch and 9-12ths (45 millim. nearly) ; diameter, 9-12ths of an inch 

 (19 millim.) 



Localities. — Bracklesham Bay, where it is very rare. French : Grignon, Parnes, 

 Mouchy (fide Desh.), Chaumont, Lattainville, Gomerfontaine, Mouy, Saint-Felix, 

 Ully-Saint-Georges, La Croix blanche near Chambors (fide Graves). 



Genus 27th. Borsonia. Bellardi, 1837. 



Cordieria. Pouault, 1848. 



Among the fossil shells found in the Miocene beds of Turin, occurs one species 

 possessing all the general characters of Pleurotoma, that is to say, an elevated, pointed 

 spire, a lengthened straight anterior canal, and a wide semicircular sinus, placed in 

 the depressed posterior margin of the whorl, but distinguished from the true Pleuro- 

 toma by the presence of a single fold on the columella ; and Bellardi, influenced by the 

 importance generally attributed to the presence or absence of undoubted folds on the 

 columella, was induced to establish the present genus for the reception of the species 

 in question. It has been seen that among the English Pleurotomee before described are 



