NATICA. TRACHELIPODA. 50 
four volutions, in most species prominent, but not produced 
nor elongated ; in some instances it is very small, marginal, 
and hardly perceptible; aperture always very large, its 
margin entire, and united above, longitudinal for the most 
part, and in some species almost orbicular, in others more 
elongated ; and hardly modified or altered in form by any 
portion of the body volution ; internal cavity marked by 
two muscular impressions, seldom distant, nearly marginal. 
Stomatia inconspicua. Plate V. fig. 12. Found in the 
mountain limestone, at Bolland. 
The above generic character combines the Stomatia and Stomatella of 
Lamarck, as neither of these have distinctions sufficient to entitle them to be 
separated, and we have followed Sowerby in forming a union between these 
genera. 
All the shells of this genus are marine, and inhabit the East Indian seas, 
and coasts of New Holland. 
This is the only fossil species with which we are acquainted, it is the Plewro- 
tomaria inconspicua of Phillips. 
Genus LXIV.— SIGARETUS, — Lamarck. 
Generic Character.— Shell suborbicular, oblique, ear- 
shaped, for the most part depressed; spire very small, 
depressed, consisting of one or two rapidly enlarging volu- 
tions, and situate near the margins; aperture entire, large, 
much expanded, oblique, and longer than wide, with its 
margins disunited above, in consequence of the outer lip 
embracing its increment, the lower portion of the body; 
two muscular impressions within, the one at the upper 
and the other at the lower end; outer lip smooth on the 
margin; inner lip spirally twisted, for the most part 
reflected above, and when largely so producing a small sub- 
umbilicus behind. 
Sigaretus canaliculatus. Plate 1V. fig, 22, Found in 
the London Clay at Hordwell. 
The Sigareti bear a general resemblance to the Stomatie, but the substance 
of them is totally different, those of the present genus being always thick, and 
never pearlaceous internally ; besides, the aperture is always modified by the 
body, and they are known from Natica by the width of their aperture. 
The species of Sigareti are few in number, they inhabit the ocean, and 
are internal, or subinternal shells. 
Fossil species occur in the London Clay at Barton, and in the contempo- 
raneous formations of Italy and France, also in the Calcaire-grossier at 
Grignon, in France. 
Genus LX V.— NATICA. — Adanson. 
Generic Character, — Shell subglobose, oval, or oblong, 
