PROSOBRANCHIATA. 309 
deep, and triangular, is placed on the shoulder, and the columella is twisted, and bears 
a single, oblique, and obscure, fold-like callus near the middle.* 
This, as well as the preceding, species presents a close analogy with a Pleurotoma 
from the lower Eocene deposits of Germany, figured, but not as yet described, by 
Beyrich (‘ Norddeuts. Tertidrgeb.,’ tab. xxix, fig. 3); and for the reasons before stated, 
the identity cannot he satisfactorily ascertained. 
Size.—Axis, 7-12ths to 9-12ths of an inch, nearly ; diameter, rather more than 
3-12ths of an inch, nearly 4-12ths. 
Localhities—Highgate, Potter’s Bar. 
No. 235. Pxirvroroma pariuis. F. E. Edwards. Tab. XXXI, fig. 10, a—e. 
P. testa oblonyo-fusiformi, undique concentrice lineata : spird sub-conicd elevatd : an- 
Sractibus convexiusculis, ad humeros obtuse angulatis, inermibus ; marginibus posticis latis, 
concavis, ad suturam exilissime crenulatis ; ultimo anfractu sub-conico, in canalem brevem, 
latiusculum, prolongato ; lineis concentricis confertis, supra partes anticas mediasque anfrac- 
tium inequalibus, lineis incrementi asperatis ; supra margines regularibus, granulatis : 
apertura oblongo-ovali ; labro tenui, sub-semicirculart ; sinu profundo, marginibus sub-paral- 
lelis, ad humerum collocato ; columelld contortd, callosd. 
Shell elongated, fusiform, and covered with numerous, fine, concentric, raised 
lines ; the spire, formed of seven or eight volutions exclusive of the pullus, is pointed, 
nearly conical, and moderately elevated, equalling the aperture in length. The whorls 
are slightly convex, with broad, concave margins, and are separated by a deep, well- 
defined suture, along the edge of which they present a series of fine crenulations, which 
give a wrinkled appearance to the margin ; in the early whorls the margins overlap 
the preceding whorls up to the shoulders, but in the later whorls the shoulders ave 
more exposed. The last whorl is nearly conical, and terminates in front in a mode- 
rately wide and short, but distinct, canal. The concentric lines are closely set ; over 
the front and middle of the whorls they are irregular and unequal, very slender 
lines alternating with thicker, thread-like lines, and they are roughened, almost 
granulated, by the lines of growth; over the margins and shoulders, the concentric 
lines are even, regular, and finely granulated. The aperture is of an oblong-oval 
form; the outer lip is much arched, almost semicircular, thin, sharp on the edge, and 
smooth within, and it presents at the shoulder a wide and very deep sinus, with 
nearly parallel margins and a rather widely rounded extremity; the columnella is 
slightly twisted, and bears about the middle an obscure, oblique, fold-like callus. 
* The callus on the columella of P. granata, P. parilis, and of some other shells referred to Pleurotoma, 
suggests the propriety of placing those species among the Borsonie ; but this callus is not, in fact, a true 
fold, but merely a thickening caused by the contortion of the columella; and, therefore, the species in 
which it is found are carefully excluded by Bellardi from his genus. 
