PROSOBRANCHIATA. 299 
No. 223. Pirurotoma roretta. J. £. Edwards. Tab. XXXI, fig. 4, a, 4. 
P. testa turritd, longitudinaliter arcuato-costellata, undique transversim sulcatd : spird 
elata, acuminata: anfractibus sub rectis, ad humeros angulatis ; postice concavis, granulato- 
marginatis ; ultimo anfractu antice repente courctato, sub-angulato, in canalem brevem, latius- 
culum, emarginatum, producto ; costellis distantibus, angustis, ad basin tendentibus, sepe 
bifurcatis, postice sub-tuberculosis ; sulcis transversis supra margines posticas et humeros 
confertis, angustis ; caeterum latioribus, distantioribus: aperturé obovatd ; labro arcuato ; 
sinu lato, profundo, sub-semicirculari, ad humerum collocato. 
A rather wide, turreted shell, longitudinally ribbed, and concentrically furrowed : 
the spire is pointed, much elevated, being nearly twice the length of the aperture, and 
formed of four or five volutions, exclusive of a smooth, lengthened, sub-cylindrical pullus. 
The whorls are nearly straight-sided, and angulated at the shoulders ; the posterior 
margins narrow, concave, and slightly thickened round the suture, where they present 
a series of small, rounded, rather distant tubercles ; the last whorl is suddenly con- 
tracted, so as to become obtusely angulated towards the front, and it terminates in a 
short, but distinct, and moderately wide canal, the anterior extremity of which is 
notched. The costelle are rather distant, curved and narrow, and are swelled on the 
shoulders into small, oblong tubercles; thence they taper gradually, becoming sharp 
and elevated lines, not unfrequently furcated, towards the front, and they extend to 
the very base of the whorl ; the concentric furrows are narrow, shallow, close-set, and 
regular over the posterior margins and shoulders, but are wider, deeper, and more 
distant over the middle and front of the whorls. The aperture is nearly oval ; the 
outer lip thin, sharp-edged, and arched; and the sinus, which is on the shoulder, is 
wide, moderately deep, and rounded at the extremity. 
This species presents some analogy with two Pleurotome from Cuise Lamotte, at 
present undescribed, but which have been named respectively P. plicatel/a and P. 
normalis by M. Deshayes, to whom I am indebted for specimens ; in the first of these 
species, however, the shell is more slender, the spire more conical and pointed, the 
whorls more regularly convex, the posterior margins not so deeply channeled, the 
anterior canal longer, and the sinus wider and more trigonal ; and in P. zormalis the 
shell is wider, the spire more conical, the posterior margins of the whorls deeper 
and simple on the sutural edge, the costee more distant and shorter, and the canal 
longer ; the transverse ornamentation also consists of very slender, closely set, raised 
lines, and the sinus is placed in the margin. 
Size. 
Localities—Highcliff, where it is not uncommon, and Barton, where it appears to 
be very rare. 
Axis, 5-12ths of an inch; diameter, 2°5-12ths of an inch. 
