PULMONATA. 101 
P. testé levi sub-striatdve, superné sub-pland, subtus concavd ; anfractibus sex vel 
septem, rotundatis, viv involventibus, inferné ad marginem umbilicalem sub-angulatis ; suturis 
profundis : apertura parum obliqua. 
A rather large shell, formed of six or seven nearly round volutions, separated by a 
deep suture, and each slightly impinged upon by the preceding one; the volutions 
are flatly convex on the upper sides, convex beneath, and, like those of P. exomphalus, 
present an angle running round the inner margins near the umbilicus, which, as the 
shell approaches maturity, becomes almost obsolete. The upper face is nearly flat ; 
while the under side presents a moderately deep and wide concavity. The aperture 
is transversely oval, and but slightly oblique. The strize of growth are very conspi- 
cuous; and occasionally, although very rarely, the shells present fine concentric lines, 
similar to those which characterise ?. ewomphalus ; in this species, however, the lines 
are finer and more crowded, and seldom extend beyond the first three or four 
volutions. 
Brard states that, in P. arrondi, the whorls are perfectly round, and do not impinge 
upon the succeeding whorls; and in these respects his shell does not agree with the 
English specimens; but the figures, apparently, are taken from a cast, and the dis- 
agreement may probably be attributed to that circumstance. Brogniart’s fig. 4, (var. 
A, of that author,) agrees very well with our specimens, except that the aperture is 
more oblique. In the figure given by M. Deshayes, the whorls are wider and more 
flattened on the upper surface, and the upper margin of the aperture appears to be 
more produced than in any English specimen I have seen; the shell, too, is larger 
than our shells, and, in fact, strongly resembles those specimens of P. ewomphalus in 
which the characteristic angle round the whorls has become obsolete. 
The general resemblance and the distinctions between the present species and the 
recent P. corneus, have been pointed out by the French authors cited; and, on com- 
paring the two, it will be seen that in the latter species the whorls are fewer, rounder, 
and enlarge more rapidly, and that in consequence, the shell is deeper and more 
largely umbilicated than the fossil species. 
MM. Ferussac and Deshayes mention a variety (probably the var. B of Brogniart) 
in which the shell is smaller, rather more compressed, and nearly equally concave 
above and below; | have not met with this variety among the English specimens. 
Size.—Diameter, 1 inch and 2-10ths. 
Localities —English: Sconce; Headon Hill; Hordwell. French: Aurillac, La 
Vissiere, Lavergnol, in the Cantal; Saint-Prix; Palaiseau, Milon near Versailles; Triel; 
Fontainbleau; La Villette. 
