﻿300 



EOCENE MOLLUSCA. 



No. 224. Pleurotoma cedilla. F. E. Edwards. Tab. XXXI, fig. 5, a, b. 



P. testa turritd, tuberculatd, undique transversim lineatd .- anfractibus convexiusculis, 

 ad /turner os obscure angulatis,plicatis ; postice concavis, tuberculato-marginatis ; ultimo an- 

 fractu antice in canali lato, breviusculo, terminato ; plicis numerosis, angustis, brevibus, ar. 

 cuatis ; lineis iransversis regularibus; supra mar gines et humeros confertis, filiformibus, aqua- 

 libus ; caterum crassioribus, distantioribus : aperturd oblongo-ovali ; labro aliformi, ad 

 humerum late breviterque sinuato. 



Shell turreted, tuberculated, and concentrically lined ; the spire pointed, moderately 

 elevated, barely equalling the aperture in length ; the whorls, six or seven, exclusive 

 of a small, conical pullus of two volutions, slightly convex, obscurely angulated on 

 the shoulders, and armed with a row of rather numerous, short, curved, pliciform 

 tubercles ; the posterior margins are slightly hollowed, and are thickened round the 

 sutural edge, which is girt by a row of small, knob-like tubercles, not very distant from 

 each other ; the last whorl is much contracted in front, and produced into a rather wide 

 and short but distinct, and oblique, canal, notched at the anterior extremity. The 

 transverse lines over the shoulders and posterior margins of the whorls are slender, 

 depressed, regular, equal, and close-set ; those over the middle and front of the body 

 whorl are coarser, and more distant, being separated by spaces as wide as themselves ; 

 they are somewhat undulating, and are roughened by the lines of growth. The 

 aperture is of an oblong-oval form ; the outer lip wing-shaped, projecting at the 

 middle, thin, sharp-edged, and smooth within ; and the sinus, which is wide, not very 

 deep, and almost semicircular, is placed on the shoulder. 



The present species is distinguished from P. rotella by the longer and more convex 

 whorls, the short and curved folds on the shoulders, the wider and somewhat longer 

 anterior canal, and the broader and shallower sinus. Like that species, it presents an 

 analogy with P. normalis (Desh., sp. ined.), but the wider and straighter posterior 

 margins, with their simple sutural edge, and the more sharply angulated shoulders of 

 the whorls, the more slender and regular concentrical lineation, and the marginal 

 position of the sinus of the latter shell, render the two species easily separable. 



Size. — Axis, 6-12ths of an inch; diameter, rather less than 3-12ths of an inch. 



Localities. — Barton and Alum Bay (Strat. No. 29, Prestw.), at both of which places 

 it appears to be rare. 



