GASTEROPODA PECTINIBRANCHIATA. 
363 
an oval ; and its aperture in the adult animal is transversely toothed on each side. The cloak is suffi- 
ciently ample to fold over and envelope the 
shell, which, at a certain age, it covers with a 
layer of shell of another colour ; and from this 
circumstance, joined to the change which the 
aperture undergoes, the full-grown shell may be 
'mistaken for another species. The animal has 
moderate tentacula, with the eyes at their ex- 
ternal bases, and a thin foot without an oper- 
culum. 
The colours of the shells are very beautiful, and 
many species are found in our cabinets, though, with 
very few exceptions, they all inhabit the seas of tro- 
pical countries. [Bruguiferes was of opinion that the 
animal of the Cypraea, before it arrived at its complete 
growth, abandons its shell several times, to form 
another more fitted to its dimensions. This opinion 
is now relinquished.] 
The Ovul^, Brug. — 
Have an oval shell, with a narrow, lengthened 
aperture, as in Cyprsea, but without teeth on the columellar side ; the spire is concealed, and the two 
ends of the aperture are nearly equally emarginated, or equally prolonged into a canal. Linnaeus con- 
founded them with Bulla, from which they were properly separated by Bruguieres. Their snail has a 
broad foot, an expanded cloak, which partly folds over the shell, a moderate and obtuse snout, and two 
long tentacula, on which we find the eyes at about the third of their length on the outside. Montfort 
restricts the name Ovula to such shells as are transversely denticulated on the outer lip ; and he names 
those in which the two ends of the aperture are prolonged into a canal, and the outer lip is plain, the 
Volva. When this lip is also plain, without a prolongation on each side, he calls the genus Calpurna. 
Fi?. 176- — Cyprsea exanthema. 
Terebellum, Lam. — 
Has an oblong [or subcylindrical] shell, with a narrow aperture, without plaits or grooves, and 
increasing regularly in width to the end opposite the spire, which is more or less salient, according to 
the species. The animal is not known. [On account of its hidden spire, Montfort separates the 
species named Convolutum, by Lamarck, to form his genus Seraphs, which seems to be unnecessary.] 
The Volutes {Voluta, Linn.) — 
Vary in the figure of the shell and of the aperture, but are recognized by the emargination without a 
canal which terminates it, and by the oblique plaits of the columella. 
Bruguieres first separated from them the Oliva, so named from the oblong or elliptical form of the shell, whose 
mouth is straight, long, and sinuated opposite tothe short spine, and the plaits of the columella are numerous and 
similar to striae. The whorls are separated from each other by a narrow groove. These shells do not yield in beauty 
to the Cowries. Their animal has a large foot, the anterior part of which (in advance of the head) is separated by 
an indentation on each side : the tentacula are slender, and the eyes are on their side near the middle of their 
length. The pi*oboscis, the siphon, and penis are tolerably long: they have no operculum. MM. Quoy and 
Gaymard have observed at the posterior part of the foot an appendage, which is laid in the furrow of the whorls. 
The remaining species of the Volutes have been subdivided into five genera by M. de Lamai'ck. The Volvaria 
nearly resemble Oliva in their oblong or cylindrical form ; but their aperture is narrow, and its anterior margin 
rises even above the spire, which is extremely short. There are one or several plaits on the columella. Their 
polish and whiteness has induced the natives of some countries to string them into necklaces. There is a small 
fossil species in the environs of Paris. [According to Sowerby, Volvaria is entirely a fossil genus, of which two 
species are found in the environs of Paris, and one in the London clay at Hordwell.] Voluta, Lam., has an ample 
aperture, and a columella marked with some large plaits, of which the inferior is the strongest. Their spire varies 
much in its prominence. Some {Cymbium, Montf. ; Cymba, Sowerb.) have the last whorl ventricose : their animal 
has a large, thick, fleshy foot, without an operculum ; and over the head a veil, at the sides of which the tentacula 
issue. The eyes are seated on this veil, exterior to the tentacula. The proboscis is of considerable length, and the 
syphon has an appendage on each side of its base. The shells attain a great size, and several are very beautiful. 
[“ The shells are ventricose, light, and buoyant, floating when placed iipon their backs on water, and having when 
so placed a boat-like appearance. Their apex is rude, and without regularity of shape. They are sombre, and, 
for the most part, uniform in colour. They are covered with a smooth brown epidermis, which is, again, more or 
