﻿294 



EOCENE MOLLUSCA. 



and shoulders of the whorls are rather thick, equal, regular, and not very prominent ; 

 over the middle they are elevated, more distant, separated by concave spaces as 

 wide as the lines themselves, and granulated ; the last whorl is much contracted 

 in front, and terminates in a wide and short, but distinct, canal. The aperture is 

 widely ovate ; the outer lip but slightly arched, thin, and sharp-edged, and smooth 

 within; the sinus is moderately deep, rather wide and triangular in form, and 

 placed on the shoulder. 



The present Pleurotoma closely resembles P. monerma, but the plications on the 

 shoulders of the whorls are very distinct in character, and the transverse lineation in 

 this species is bolder, coarser, and more closely set; the aperture is more widely oval, 

 and the sinus also is neither so deep nor so wide. These differences appear to be 

 constant, for although possessing a good series of each species, I do not find specimens 

 presenting intermediate characters, and in a comparison of the two series the eye at 

 once recognises the distinctions. 



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



Locality. — Highcliff. 



No. 218. Pleurotoma abnormis. F. E. Edwards. Tab. XXX, fig. 14, a, b. 



P. testa sub-turritd, sub-conicd, longitudinaliter costatd, omnino concentrice sulcata: spird 

 productd, obtusiuscidd : anfractibus convexiusculis, postice canalicidatis, suturd undulatd, 

 simplici divisis ; ultimo anfractu in canali angusto, sub-obliquo terminato ; costis sub-dis- 

 tantibus, lovgis, rotundatis, postice obliquis, ad humeros angulatis, antice curvis, attenuates ; 

 sulcis numerosis, stib-aqualibus : aperturd ob-ovatd ; labro leviler arcuato, acuto ; sinu 

 fatissimo, minime prof undo, triangulari, ad humerum collocato. 



A turreted, nearly conical shell, longitudinally ribbed, and having the whole surface 

 covered with concentric furrows : the spire rather obtuse and much produced, being 

 nearly half as long again as the aperture. The whorls, eight or nine in number, are 

 very slightly convex, channeled round the posterior margin, and separated by a 

 simple suture, rendered undulating by the ribs of the preceding whorl. The ribs are 

 rather numerous (twelve or thirteen), depressedly convex on the upper surface, 

 long, extending from the suture to the canal, and separated by spaces equalling the 

 ribs in width ; on the margin the ribs are very oblique, but they are bent at a slightly 

 obtuse angle when they reach the shoulder, whence they are prolonged, and become 

 much attenuated towards the front of the shell, forming a gentle curve corresponding 

 with the outline of the outer lip. The concentric furrows are numerous, regular, 

 moderately deep, rather narrow, and separated by bands somewhat wider than the 

 furrows, and rounded on the upper surface. The aperture is nearly oval, and 

 terminates in front in a short, slightly oblique, and narrow canal ; the outer lip is 



