﻿•270 



EOCENE MOLLUSCA. 



spire, the short, nearly conical whorls, the broad, upright ribs, the distant, transverse 

 lineation, and the short, anterior canal, render it easily distinguishable. I dedicate 

 the species to the Rev. Osmond Fisher, the rector of Elmstead, near Colchester, 

 a zealous and indefatigable fellow-labourer in this branch of Eocene Palaeontology, 

 to whose researches I am indebted for the discovery of the locality from which 

 the species has been obtained. 



Size. — Axis, not quite 5-12ths of an inch; diameter, 2-12ths of an inch nearly. 



Locality. — Brook (New Forest). 



No. 193. Pleurotoma T allavignesii. Rouault. Tab. XXXIII, fig. 9, a, b. 



Pleurotoma Tallavignesii. Rouault, 1848. Descr. des Foss. dii Terr. Eocene des Env. 



de Pan ; (Mem. Soc. Geol. de France, vol. iii, 2d ser., 

 p. 482, t. 16, figs. 18, 19.) 



P. testa elongato-fusiformi, turritd, transversim irre.gulariter lineatd, longitudinaliter 

 costellatd : anfractibus convexiusculis, angulatis ; postice concavis, ad suturam marginatis ; 

 costellis numerosis, angustis, obliquis, bifurcatis • aperturd elongato-angustd, in canalem 

 rectum longiusculum productd ; labro arcuaio ; sinu lato, sub-trigono, in margine collocato. 



Shell elongated, fusiform, turreted, longitudinally ribbed, and concentrically lined ; 

 the spire moderately elevated, not equalling the last whorl in length : the whorls 

 rather deep and slightly convex, almost flat-sided, and sharply angulated at the 

 shoulders ; the posterior margins wide, slanting, concave, and thickened along the 

 sutural edge, where they present either three or four prominent, raised lines, or 

 a narrow, ribbon-like band, sometimes bisected by a concentric furrow : the whole 

 surface between the suture and the shoulders is ornamented by a series of curved 

 plications, caused by the successive edges of the advancing sinus. The longitudinal 

 ribs are numerous, narrow, oblique, much curved, and short, not extending beyond 

 the middle of the whorls ; they are not very prominent, and most frequently bifurcate 

 shortly after their origin on the shoulders ; the last whorl is much produced in front, 

 where it forms a longish and moderately wide canal. The aperture is of a lengthened 

 oval form ; the outer lip is much arched, and presents in the posterior margin a 

 widely sub-trigonal sinus. 



The present species affords another instance of the identity of forms hitherto 

 found only in the Lower Eocene deposits in England with forms characteristic of 

 the Nummulitic Beds of France ; but the English specimens agree so well with the 

 figures and description given by Rouault, and more especially with his Var. «, that 

 the identity can scarcely be questioned. 



I have already pointed out the differences between the present species and 

 P. pgrgota, the only English Pleurotoma which resembles it. 



