﻿PROSOBRANCHIATA. 



285 



hollow space between the suture and the shoulder is traversed by several irregular, 

 shallow, almost obsolete furrows. The body whorl is much contracted in front, whence 

 it tapers gradually to the base, forming a long, wide, and nearly straight canal : four or 

 five concentric lines cross the middle of the last whorl ; these lines are rounded, 

 rather distant, and separated by wide concave spaces ; over the front of the whorl, 

 and as they descend the canal, the concentric lines become gradually closer and less 

 prominent, and at last are almost obsolete on the anterior extremity of the canal. 

 The aperture is of an oblong-oval form ; the outer lip arched, somewhat wing-shaped, 

 projecting slightly towards the posterior extremity ; and the sinus, which is placed 

 on the shoulder, is rather wide, very deep, and triangular. 



In the series forming part of Mr. Wetherell's collection, two or three specimens 

 occur in which the line of the suture being less decurrent, the margins of the whorls 

 extend quite up to the shoulders ; the shell, consequently, is a little wider, and the 

 spire not so much elevated ; but this difference appears to be accidental and scarcely 

 constitutes a variety. 



Size. — Axis, 1 inch and 1 -8th ; diameter, not quite 4-12ths of an inch. 



Localities. — Highgate Archway, Cuffell. 



No. 211. Pleurotoma Wetherellii. F. E. Edwards. Tab. XXIX, fig. 16, a—d. 



P. testa elongato-fusiformi, costellatd, undique spiraliter lineatd : spud mediocriter 

 elatd, sub-conicd: anfractibus sub-angtdatis, suturd perspicud separatism antice eonvexius- 

 culis ; marginibus posticis latis, sub-recth ; costellis numerosis, curvis ; lineis spiralibus 

 medianis distantibus, crassis, pra-emhientibus ; cceteris fdiformibus, crebrioribus : aperturd 

 obtongo-ovali, in canali longo exeunti ; labro arcuaio ; sinu lato, prof undo, ad humeruvi 

 collocato. 



Shell elongated, fusiform, ribbed and concentrically lined ; the spire moderately 

 elevated, rather thick, and nearly conical : the whorls, seven or eight, bluntly angu- 

 lated at the shoulders, and slightly convex in front ; the posterior margins wide and 

 nearly straight. The ribs vary much in size, being more or less lengthened in the 

 direction of the axis in different individuals ; the concentric lines over the middle of 

 the whorls are more or less distant, thick, and very prominent ; over the shoulders 

 and posterior margins they are finer, thread-like, more closely set, and irregular. The 

 aperture is oblong-oval in shape, and terminates in front in a long, wide, and slightly 

 oblique canal; the outer lip is much arched, thin and sharp on the edge, and 

 smooth within; and the sinus is moderately wide, deep, sub-trigonal, and placer! 

 on the shoulder. 



A variety occurs in which the posterior margins of the whorls are narrower, and 

 the sutural edges slightly thickened. 



