Nerita. 
MOLLUSCA. 
91 
Spherical, depressed, smooth; spire short, consisting of two 
inflated volutions, their upper edges furnished with a concave, 
transversely striated groove or hand, with a blunted apex; um¬ 
bilicus large, circular, gradually expanding into the base of the 
body. 
Found in the Gault at Folkstone, Kent. 
22. Natica elegans. —The Elegant Natica, pi. XXXIII.* 
fig. 21. 
Natica elegans. Sowerby, Geo. Trans. IV. 2nd series, p. 
347, pi. 23, fig. 3. 
Oblong, smooth ; spire small, with four flat-sided volutions, 
their upper edges a little rounded, ending in an acute point; 
aperture somewhat more than two-thirds the length of the 
shell. 
Found in the Portland Stone, Vale of Wardour, South Wilt¬ 
shire. 
23. Natica carinata. —The Keeled Natica, pi. XXXIII.* 
fig. 22, 23. 
Natica carinata. Sowerby, Geo. Trans. IV. 2nd series, p. 
343, pi. 18, fig. 8. 
Shell transversely ovate; body very large, flattened above; 
spire small, with two volutions, placed obliquely to the base of 
the shell, and obtuse at the point; body provided with five pro¬ 
minent and rugged keels, which terminate on the margin of the 
widely expanding outer lip, and forming a scolloped edge; aper¬ 
ture very large, semilunar; inner lip very broadly reflected on 
the columella. 
Found in the Sands of Blackdown, Devonshire. 
24. Natica granosa. —The Granular Natica, pi. XXXIII.* 
fig. 24, 25. 
JSatica granosa. Sowerby, Geo. Trans. IV. 2nd series, p. 
343, pi. 18, fig. 7. 
Subglobose; body very large, much inflated, and covered 
with numerous, regular, spiral, rounded ridges, which are cros¬ 
sed by many longitudinal striae, or lines of growth, producing 
rounded granulations; spire small, consisting of three well 
rounded, rapidly diminishing volutions, ending in a sharp point; 
aperture oblong, slightly twisted, contracted above, and orbicu¬ 
lar below; outer lip much dilated; inner lip broad, with a large 
open umbilicus behind it. 
Found in the Sands at Blackdown, Devonshire. 
Genus XLI V. —NERITA.— Lamarck. 
Shell solid, generally thick, semiglobular, or obovate; 
spire very short; base of the body for the most part flat¬ 
tened beneath, but destitute of an umbilicus; aperture 
semicircular; margin of the outer lip sharp, and cumu¬ 
lated, or toothed on the inner side; pillar lip generally 
oblique, flattened, sharp on the margin, which lies ob¬ 
lique to the axis of the shell, and for the most part den- 
tated or crenated; a small prominence exists at the lower 
extremity of the inner lip, between which and the inner 
lip the small appendage to the operculum slides, as the 
animal opens or closes the aperture for egress; moving 
in the same manner as a door on its hinges, when the 
animal protrudes its body; operculum testaceous. 
1. Nerita costata —The Ribbed Nerita, pi. XLIV. fig. 
1 , 2 . 
Nerita costata. Sowerby, V. p. 94, pi. 463, fig. 5, 6. Fle¬ 
ming, p. 319. 
Shell nearly globular; spire much depressed, consisting of 
two volutions, with a canaliculate suture; whole surface covered 
by numerous, thin, sharp, longitudinal ribs; aperture nearly 
orbicular, much expanded; outer lip rather thickened; pillar 
somewhat produced, and obtuse, and nearly divided by a slight 
sinus into two blunt teeth. 
Found in the Oolite at AnclifFe. 
2. Nerita l,evigata —The Smooth Nerita, pi. XLIV. 
fig. 3, 4. 
Nerita Icevigata. Sowerby, III. p. 31, pi. 217, fig. 1. Fle¬ 
ming, p. 318. 
Subglobose, smooth, glossy; spire conical, consisting of two 
slightly divided, flat-sided volutions; body invested by a sub¬ 
central, nearly obscure, transverse sulcus; base convex; aper¬ 
ture sublunate, its width greater than its length; outer lip 
smooth-edged; columella obscure. 
Found in the Oolite at Dundry. 
3. Nerita minuta— The Minute Nerita, pi. XLIV. fi<*. 
5, 6, 7. 
Nerita minuta. Sowerby, V. p. 93, pi. 463, fig. 3, 4. Fle¬ 
ming, p. 318. 
Orbicular, smooth; spire obscure, much depressed, consisting 
of one volution and a half; aperture oval; outer lip blunted; 
pillar lip destitute of any appearance of teeth. Diameter not 
an eighth of an inch. Fig. 7, natural size. 
Found in the Oolite at AnclifFe. 
4. Nerita aperta —The Open Nerita, pi. XLIV. fig. 
8, 9. 
Nerita aperta. Sowerby, V. p. 30, pi. 424, fig. 2, 3, 4. 
Fleming, p. 318. 
Suborbicular, smooth, with acutely zigzag brown lines, which 
are equal in thickness to the white intervals between them; 
spire depressed, with two volutions; aperture wide, semilunate; 
outer lip much thickened, its edge sharp and even; inner lip 
broadly reflected on the columella, its inner edge obscurely cre¬ 
nated, and furnished with one large tooth. 
Found in the London Clay at Cow r ell Bay, Isle of Wight. 
5. Nerita globosa. —The Globular Nerita, pi. XLIV. 
fig. 10, H. 
Nerita globosa. Sowerby, V. p. 29, pi. 424, fig. 1. Fle¬ 
ming, p. 318. 
Suborbicular; spire hardly elevated above the body,with two 
volutions; aperture somewhat orbicular, within which, near its 
lower end, a lamelliform tooth ; outer lip thin, destitute of cre- 
nulations; pillar lip narrowly reflected on the columella above, 
but wider below, provided with one very obtuse tooth near its 
upper end; whole surface transversely sulcated. 
bound in the London Clay, Hampshire. 
6. Nerita spirata. —The Short-spired Nerita, pi. XLIV. 
fig. 24, 25. 
Nerita spirata. Sowerby, V. p. 93, pi. 463, fig. 1, 2. Fle¬ 
ming, p. 319. 
Subglobose, smooth; spire very small, in proportion to the 
size of the shell, consisting of two volutions, and with an 
obscure canal round their base; body extremely large, broadly 
