GASTEROPODA PECTINIBRANCHIATA. 



363 



Kii*. 176. — Cyprgea exanthema. 



an oval ; and its aperture in the adult animal is transversely toothed on each side. The cloak is suffi- 



p. ciently ample to fold over and envelope the 



iw ^ 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 lie 

 mistaken for another species. The animal baa 

 moderate tcntacula, 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, w ith 

 very few exceptions, they all inhabit the seas of tro- 

 pical countries. [Brugnieres 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.e, Drug. — 

 Have an oval shell, with a narrow, lengthened 

 aperture, as in Cypraea, 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 Brugnieres. 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 arc 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 

 Volta. When this lip is also plain, without a prolongation on each side, he calls the genus L'alpurna. 



Terebkllum, Lam. — 

 Has an ohlong [or Buhcylindrical] 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 Convolution, by Lamarck, to form his genus Seraphs, which seems to he unnecessary.] 



The Volutes (Volufa, 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. 



liruguieres first separated from them the O/iia, so named from the ohlong or elliptical form of the shell, whose 

 mouth is straight, long, and sinuated opposite tothe short spine, and the plaits of the columella air RUUMfUUS and 

 similar to striae. The whorls are separated from each other liy a narrow groove. These sheila <l<> not yield in beauty 

 t i the Cowries. Thar 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 ryes are on their side near the middle of their 

 length, 'the proboscis, the siphon, and penis are tolerably long: they have do operculum. MM. Quo] and 

 Gay u i a rd have observed at the posterior part of the fool an appendage, which is laid in the furrow of the whorls. 



The remaining specie- of the Volutes have been subdivided into Ave (jenera by If. de Lamarck. The Vohxaia 

 nearly resemble ( Miva 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 lias induced the natives ,.(' some countries to String them into necklaces. There is a small 



I species in the environs of Paris. [According to Sowerby, Volvaria is entirely a t'ossii jrenna, of which two 

 species are found In the environs of Paris, and one in the London da] 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 m its prominence. Some (CymMtt**, Uontf. ; CyvUta, Sowerb.) have the last whorl vent -<■ : their animal 



has a large, thick, fleshy foot, without an operculum ■, and over the head ■ veil, at the sides of which the tentacula 

 issi;,-. The eyes .we seated on tins veil, exterior to tin i mtacula. The proboscis is of considerable length, and the 

 syphon has an appendage on each side of its base. The shells attain s great siaa, at d si veral are vei > beautiful. 

 [" The shells are renti ii ose, light, and buoyant, floating when placid upon their backs on water, and having when 

 so placed a boat-like appearance. Their apex is rude, and without regularit) of shape. Thej an • 



for the most part, u in form m colour. They are coveied with a smooth brown epidermis, which Is, again, BtOBJ r 



