﻿PROSOBRANCHIATA. 



327 



No. 249. Borsonia Biaritzana. Rouault. Tab. XXXIII, fig. 11, a, b. 



Borsonia Biaritzana. Rou. 1848. Bull, de la Soc. Geol. de France, 2 e serie, vol. v, p. 20". 



— Palensis. Rou. 1848. Idem. 



Cordieria Biaritzana. Rou. 1848. Desc. des Foss. du terr. Eocene, des Env. de Pau 



(Mem. Soc. Geol. de France, 2d series, vol. iii, p. 488, 

 tab. 17, fig. 5, a, 6, a). 



Pleurotoma curvicosta. Sow. (non Lamlc.) 1850. Dixon's Geol., &c, Sussex, p. 183, 



tab. 7, fig. 17. 



— — Morris, 1854. Cat. Brit. Foss., p. 270. 



Fasciolaria biplicata. Sow. 1850. Dixon's Geol., &c, Sussex, p. 184, t. 5, fig. 7. 



— — Morris, 1854. Cat. Brit. Foss., p. 248. 



B. testa elongato-fusiformi, turritd, longitudinaliter nodoso-costatd, spiraliter Uneatd -. 

 spird acuminata, elevatd, in longitudine aperturam paullo superanti : anfractibus convexis, 

 postice canaliculatis ; costis latis, rotundatis, brevibus ; lineis spiralibus crebris, Jiliformibus : 

 aperturd oblongo-ovatd, antice in canali lato brevique exeunte ; labro sub-recto, in margine 

 sinuato ; sinu lato, mediocriter pro/undo, semicirculari ; columella sub-cgliudricd, biplicata. 



Shell elongated, fusiform, ribbed, and spirally lined ; the spire pointed and 

 elevated, somewhat exceeding the aperture in length. The whorls, eight or ten 

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

 terior margins slope gently backwards and are concentrically furrowed. The longitu- 

 dinal ribs are distant, very broad, rounded, and somewhat swelled, so as to become 

 almost nodulous, on the shoulder ; the concentric lines are numerous and thread-like, 

 even and regular on the posterior margins and shoulders of the whorls ; elsewhere 

 they are unequal, more prominent lines alternating with the slender lines, and all are 

 more or less strongly decussated by the lines of growth. The aperture is of an oblong 

 ovate form, and terminates in front in a very wide and short, but distinct, canal ; the outer 

 lip is nearly straight, and presents a wide but not very deep sinus, placed in the posterior 

 margin of the whorl ; the columella is somewhat cylindrical and nearly straight, and 

 presents, a little behind the middle, two slightly oblique, narrow folds, which do not 

 extend to the front of the columella, and which, consequently, are scarcely visible 

 unless the outer lip is broken off. 



The specimen figured and described by Mr. Sowerby (loc. cit.) as P. curvicosta, 

 forms part of my collection ; at that time the aperture was closed by the matrix, and 

 the columellar folds, therefore, were not detected. These folds have since been ex- 

 posed to view, and there cannot be now any doubt of the identity of Pleurotoma cur- 

 vicosta (Sow.) and Fasciolaria biplicata. 



The shells from Bos d'Arros, described by Rouault, apparently do not attain so 

 large a size as our English shells ; in them the last whorl is longer, apparently, than 



