PROSOBRANCHIATA. 169 
columella, and the basal furrows are fainter and more numerous, becoming, in fact, 
almost obsolete on the mature shell. 
The present species certainly presents a close analogy with /”. /abrella (Lamk.) to 
which the adult shells have been referred; but a careful comparison will show, I think, 
that they are not a mere local variety of that species, but distinct from it. In /. 
Selseiensis, the whorl is more convex, and the general form of the shell is consequently 
more ovate and less turbinate ; the shoulder is always obtusely rounded, and never pre- 
sents the prominent keel which characterises /. /aére//a, nor even the angular periphery 
which, in some specimens, is substituted for the keel; the transverse furrows are lost 
after the very early whorls, while in the French species they are continued more or 
less distinctly until maturity. But the principal differences will be found in the con- 
dition of the lips; for in V. dadrel/a, the outer lip is much less thickened, and does not 
assume the wing-like expansion found in the present species; the inner lip is more 
widely spread over the front of the body-whorl and, although thickened at the pos- 
terior extremity, does not form the large callus which, by separating the margin of the 
whorl from the spire, forms so conspicuous a character in /. Se/seiensis. 
Sixe-—Axis, 2 inches and 7-10ths nearly; diameter, rather more than 1 inch and 
6-10ths. 
Locality.—Bracklesham Bay, where it is not uncommon. 
Section A. (Pullus small, conical) continued. 
b. Shell fusiform ; costated, transversely striated ; inner 
lip narrow. 
a. Columellar plaits few. 
No. 108. VoLura ancusta. Deshayes. Tab. XXIII, figs. 3 a, 4. 
VoLura ANGUsTA, Desh. 1824-37. Desc. des Coq. Foss., vol. ii, p. 697; t. 94, figs. 5, 6. 
— = Sow. 1844. Min. Con., vol. vii, p. 34, t. 626, figs. 1—3. 
=: = Sow. 1850. Dixon’s Geol., &c., of Suss., p. 107, t. 5, fig. 19 (non t. 7, fig. 37). 
V. testa elongata, sub-fusiformi, angustd, costatd, ad basin late emarginatd ; spird pro- 
ductd sub-conicd, apice acuto : anfractibus depresso-conveaiusculis, superne tenuissime striatis ; 
ultimo anfractu spiram longitudine fere equanti ; postice tuberculoso-costatd, ad basin levi : 
apertura elongatd, angustd ; columelléd rectd, obscure triplicatd ; labro acuto, simplict ; 
labio angusto. 
Shell fusiform, much elongated, narrow, ribbed, and widely but not very deeply 
notched at the base ; spire conical, produced, nearly as long as the last whorl ; apex small, 
pointed: whorls depressedly convex, ornamented with exceedingly fine transverse 
striz ; ribs distant, not prominent, extending to nearly the middle of the whorl, and 
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