﻿252 



EOCENE MOLLUSCA. 



Size. — Axis, 8-12ths of an inch ; diameter, 3-12ths of an inch. 

 Locality. — Alum Bay (Stratum No. 29, Prestwich?); rare. 



No. 173. Pleurotoma dilinum. F. E. Edwards. Tab. XXVIII, fig. 15, a, b. 



P. testa minima, oblongd, fusiformi, granulatd, concentrice lineatd: spird obtusius- 

 culd, sub-conicd : anfractibus sub-convexis, duplici serie granulorum coronatis, spatio 

 inter series concavo, Icevi ; ultimo anfractu antice valde coarctato, in canalem latis- 

 simum, brevem, rejlexum producto ; lineis spiralibus, acutis, sub-distantibus -. aperturd ovali; 

 labro acuto, levitcr arcuato, intus plicato ; sinu latissimo, mediocriter pro/undo, sub- 

 trigono, anticd in margine collocalo. 



Shell very small, oblong, fusiform, spirally girt by a double row of small, bead-like 

 tubercles, concentrically lined ; spire rather thick, nearly conical ; whorls slightly 

 convex ; the posterior margins concave, smooth, bordered in front and behind by the 

 rows of tubercles ; the last whorl much contracted in front, and terminating in a 

 very wide, short, but distinct, canal, a little bent backwards ; the concentric lines 

 thin, sharp, and rather distant. The aperture is of an oval form ; the outer lip 

 slightly arched, expanding towards the front, sharp-edged, and plicated within ; the 

 sinus very wide, moderately deep, somewhat triangular in shape, and placed in the 

 front part of the posterior margin. 



This Pleurotoma is allied to P. microcheila, the var. producta of which closely 

 resembles it ; but the wide posterior margins, the greater regularity of the granula- 

 tions, and the broad anterior canal, distinguish the present species. 



Size. — Axis, not quite 3-12ths of an inch ; diameter, 1-1 2th of an inch. 



Locality. — Alum Bay (No. 29, Prestwich). 



No. 174. Pleurotoma tricincta. F. E. Edwards. Tab. XXVIII, fig. 6, a, b. 



P. testa parvd, elongato-fusiformi, sub-turritd, spiraliter lineatd : spird acuminata, 

 breviusculd, aperturam in longitudine vix aquanti : anfractibus depresso-convexis ; postice 

 profnnde canaliculatis , marginatis ; ultimo anfractu in canalem brevem, latum, producto ; 

 lineis spiralibus exilibus, filrformibus, irregularibus, sub-clathratis : aperturd oblongo- 

 ovali ; labro arcuato ; sinu lato, mediocriter prof undo, in margine collocalo. 



Shell small, oblong, fusiform, indistinctly turreted, concentrically lined ; spire 

 pointed, rather short, not equalling the last whorl in length ; whorls flatly convex at 

 the sides ; the posterior margins deeply hollowed, giving the turreted aspect to the 

 spire, and ornamented with a series of roundedly curved plications, formed by the 

 successive elevated margins of the sinus ; the sutural edge is bordered by a sharp, 

 ridge-like, raised line ; the last whorl is contracted in front, and terminates in a very 



