﻿PROSOBRANCHIATA. 



323 



of two unequal cones placed base to base, the smaller one of which is represented by 

 the spire ; the whorls, seven or eight without the pullus, are straight on the sides and 

 taper regularly towards the base ; the posterior margins slope gently backwards, con- 

 cealing the preceding whorl up to the angle of the shoulder, giving a straight-sided, 

 conical shape to the spire, which forms about two fifths of the entire length of the 

 shell. Two or three narrow, obscure furrows traverse the space between the suture 

 and the shoulders ; and the front of the last whorl also presents numerous transverse, 

 undulating furrows, the ridges between which are a little roughened by the lines of 

 growth ; the remaining surface of the whorls is smooth and shining. The aperture is 

 long and narrow, with nearly parallel margins, resembling that of a Cone, and terminates 

 in front in a wide, short, and indistinct canal, deeply notched at the anterior extremity. 

 The outer lip is much arched, and presents on the shoulder a very wide, shallow sinus, 

 with a broadly rounded apex ; the inner lip is elevated and bent outwards at the base, 

 giving an umbilicated appearance to the front of the shell ; and the columella is cylin- 

 drical and strongly crested. 



The present species is distinguished by the inequality of the two cones of which it 

 appears to be formed, and by that character and by the wide, shallow sinus it may 

 be easily separated from P. prisca, which, in other respects, it resembles. It does 

 not appear to have an analogue among the French coniform Pleurotomae. 



Size. — Axis, 2\ inches ; diameter, 1 inch. 



Locality. — Bracklesham Bay, to which it appears to be peculiar. I have not met 

 with it elsewhere, not even at Stubbington or Bramshaw. 



No. 247. Pleurotoma semistriata. Deshages. Tab. XXXIII, fig. 3 a, 3 b. 



Pleurotoma semistriata. Desk. 1824-37. Desc. des Coq. foss., &c, vol. ii,p. 443, t. 69, 



figs. 5, 6. 



Non Pleurotoma semistriata. Partsch. 1837. v. Hauer. Vorkomm. foss. Thierr. tert. Beck. v. 



Wien ; Jahrb., p. 419, No. 107. 



P. testa biconicd, transversim obsolete lineatd ; spird elatd, acuminata; anfractibus 

 convexiusculis, postice obsolete sulcatis ; ultimo anfractu gradatim attenuate, conoideo, 

 concentrice distanter et exilissime lineato, antice transversim sulcato, ad basin subprqfundc 

 emarginato : aperturd elongato-angustd ; labro acuto, aliforme, arcuato ; sinulato, trian- 

 gulari, in margine collocato. 



Shell elongated, fusiform, tapering gradually towards each extremity and presenting 

 the appearance of two cones placed base to base ; the spire moderately elevated, nearly 

 equalling the last whorl in length, and pointed. The whorls, seven without the pullus, are 

 slightly convex, smooth and shining; the posterior margins, which slope gently back- 

 wards, present two or three very shallow, nearly obsolete, concentric furrows ; the last 



