﻿274 



EOCENE MOLLUSCA. 



are covered by numerous very fine, closely set lines, either perfectly simple or feebly 

 decussated by the longitudinal lines ; and again, others in which the longitudinal 

 lines are almost obsolete. 



Size. — Axis, 1 inch ; diameter, 4-12ths of an inch. 



Localities. — Barton, HighclifF. 



No. 198. Pleurotoma conifera. F. E. Edwards. Tab. XXXI, fig. 3, a, b. 



P. tesld an gust d, elongato-fusiformi, sub-tarriid, undique spiraliter lineatd : spird 

 elcvatd, acuminata : anfractibus ad humeros sub-angulatis, in juventd tuberculalis, deinde 

 angustd iceniold cinctis ; posiice leviter cavalis, marginatis ; antice planulatis, sub-conicis ; 

 ultimo anfractu in canalem latum, mediocriter long urn, rejlexum producto ; lineis spiralibus 

 elevalis, fdiformibus, confertis, sape irrcgularibus : aperlurd sub- quadratd ; lahro ad 

 humerum sinuato ; sinu latiusculo, prof undo, sub-trigono ; columella contortd, antice 

 cristatd. 



Shell narrow, elongated, fusiform, sub-turreted, and ornamented with concentric 

 raised lines ; the spire pointed, elevated, rather exceeding the aperture in length ; 

 the whorls, seven or eight, exclusive of a small, smooth, sharply conical pullus of 

 three volutions, are slightly channelled along the posterior margins, bluntly angulated 

 at the shoulders, flatly convex at the sides, and tapering gradually towards the base ; 

 in the young state they present at the angle a row of small, vertical tubercles, but this 

 ornament is lost on the third or fourth whorl, and is thence replaced by a narrow, 

 smooth, ribbon-like band ; the posterior margins are thickened round the sutural 

 edge, which is crenulated and bordered by two spiral lines more prominent than the 

 other marginal lines. The last whorl is produced in front into a long, wide canal, 

 curved by the columella, and having the anterior extremity slightly bent backwards ; 

 the flattened sides and tapering form of the whorls impart to the spire the appearance 

 of a succession of inverted cones, gradually diminishing in size, each being half con- 

 cealed by the succeeding one. The elevated spiral lines are numerous and thread- 

 like ; sometimes they are regular and equal in size, but more frequently a very fine line 

 intervenes between two thicker lines ; and they are generally roughened by the prominent 

 lines of growth. The aperture is sub-quadrate ; the outer lip but little arched, thin, 

 sharp-edged, and smooth w T ithin; the sinus is placed on the shoulder and is deep, 

 rather narrow, and triangular in form ; the columella is slightly twisted, and at the 

 anterior extremity presents a small crest caused by the reflexion of the canal. 



The present species appears to be well-marked ; I do not know of any other 

 Pleurotoma resembling it in the peculiar form of the spire, or in the elegant con- 

 centric lineation which adorns it. It is rare. 



Size. — Axis, 10-12ths of an inch ; diameter, 3-12ths of an inch. 



Localities.— Bracklesham Bay, Bramshaw. 



