Zoological Illustrations Volume Ii Part 13

The _Marginellae_ may be divided into two sections; the first bearing in form and habit a strong resemblance to the _Cypraeae_, and the second gradually losing these indications, and acquiring those of the spiral _Volutae_. Among the first are several species, which, like the Cowries, appear dest.i.tute of any spire (as in _M. cingulata_); this part, however, begins to show itself in other successive species very progressively, until it becomes elevated and defined in _M. glabella_. This sh.e.l.l may be considered the pa.s.sage to the second division, in which the species lose the simple oval form of the first, and acquire a contracted base and pointed spire, perfectly resembling _Voluta undulata Lam._ and its allies.

The extreme developement of these characters is shown in _M. faba_.

This genus must, then, be considered as connecting those of _Cypraea_ and _Voluta_ (Lam.); excepting one, the whole of the species are very small; and as the three here selected to ill.u.s.trate these remarks are frequently seen, and have been often described under other names, little more is necessary than to detail their specific characters.

MARGINELLA cingulata,

_Banded Date Sh.e.l.l--upper figures._

_M. testa ovata, albida, lineis aurantiacis fasciata; spira obsoleta, umbilicata; columella 6 plicata._

Sh.e.l.l oval, whitish, banded with orange lines; spire obsolete, umbilicated; pillar 6 plaited.

Voluta cingulata. _Dill._ 525. 56. _Lister._ 803. _f._ 9. _Martini_, 2.

_t._ 42. _f._ 419 _and_ 20. _Gualt._ _t._ 25. _c._? 28. _b._ _Adanson_, _t._ 4. _f._ 4.

I am happy to record Mr. Dillwyn as the first systematic writer who separated this from _Mar. persicula_, which has reddish spots, and is quite a distinct species. The present is a pretty, though common sh.e.l.l, and observed by Adanson in great plenty on the African coast.

MARGINELLA prunum,

_Grey Date Sh.e.l.l--middle figures._

_M. testa ovata, grisea, immaculata; spira parva, conica; apertura fusca; columella 4 plicata._

Sh.e.l.l oval, grey, immaculate; spire small, conic; aperture brown; pillar 4 plaited.

Voluta plumbea. _Sol. MSS. L'Egouen. Adanson_, _tab._ 4. _f._ 3.

V. prunum. _Gm._ _p._ 3446. 33. _Martini_, 2. _t._ 42. _f._ 422 _and_ 3. _En. Meth._ 376. 8. _Lister_, 817. 28. (young.) _Dill._ 530. 69.

The plaits are very strong, and, together with the outer lip, white; equally common, and from the same country, as the last.

MARGINELLA faba,

_Fly-spot Date Sh.e.l.l--lower figures._

_M. testa ovata, plicata, fulva, punctis fuscis ornata; spira conica; basi emarginata; columella 4 plicata._

Sh.e.l.l oval, plaited, fulvous, with brown dots; spire conic; base notched; pillar 4 plaited.

V. faba. _Gm._ 3445. _Lister_, 812. 22. _Martini_, 2. _t._ 42. _f._ 431? 432, _and_ 3. _En. Meth._ 377. 1. _Gualt._ 28. _Q. Dill._ 528. 63.

The whorls of this pretty sh.e.l.l are plaited into little nodules; it is usually very small. The supposed variety figured by Martini, and mentioned by Mr. Dillwyn, I am inclined to believe, may be a distinct species.

Pl. 98

[Ill.u.s.tration]

PALUDINA,

_River Snail._

GENERIC CHARACTER.

_Testa ovata, spiralis, tenuis, umbilicata. Apertura semi-orbicularis, ad labii anterioris apicem subangulata. Operculum corneum._

_Animal fluviatile, branchiatum, viviparum, rostro brevissimo; oculis ad basin externam tentaculorum acutorum 2 appositis; pedis margine antico duplici; lateribus antice alis parvis instructis; ala dextera involuta in ca.n.a.lem per quem aqua in tracheam introducitur._

Typus Genericus _Helix vivipara_, Lin.

Sh.e.l.l ovate, spiral, thin, umbilicated. Aperture nearly orbicular, slightly angulated at the top of the inner lip. Operculum h.o.r.n.y.

Animal fluviatile, branchiated, viviparous; rostrum very short; eyes placed at the external base of two pointed tentacula; anterior border of the foot double; on each side the fore part of the body a small wing; that on the right side is folded into a channel, by which the water is introduced into the respiratory ca.n.a.l.

Generic Type _Viviparous Snail_ Pennant.

The common Sh.e.l.l above quoted, inhabiting many of our rivers, will serve as an excellent example of this genus, which is not numerous, and confined to fresh waters; the animals, inhabiting the European species, appear to have been thoroughly investigated by the continental naturalists; and from their account of its singular construction, the above description has been framed. Science should make no distinction of persons or countries; but it is rather mortifying to observe, that these important discoveries in the organization of animals, are pursued with zeal and ability by foreign naturalists, while most of our own content themselves with expatiating on its impossibility, and even go so far as to hint its uselessness, because we can never become acquainted with the animals of _all_ the species of sh.e.l.ls in our cabinets: so far this latter part of the argument is most true; but, to ascertain, for instance, the animal of the Cowry, it is surely not requisite we should see those of _all_ the species (near 80 in number), before we venture to describe it? any more than it is necessary completely to dissect _every_ species of Locust before we p.r.o.nounce it to be one. Science would, indeed, receive incalculable and lasting benefit, if those of our conchologists who reside near the coast would pay greater attention to the inhabiting animals, and less to the sh.e.l.ls, of their neighbourhood; for the first would supply that information they acknowledge is so desirable, and the latter would prevent our indigenous Catalogue from being crowded with many dubious, and even foreign sh.e.l.ls.

English conchologists appear not to be aware of the vast number of testaceous animals which are now known. Among those truly eminent men who have prosecuted this study, M. Adanson stands foremost, in having minutely described all those he found on the African coast; in the magnificent work of Poli nearly all the Mediterranean bivalves are exquisitely figured; and those of the land and fresh water will receive complete ill.u.s.tration from M. Ferrusac. Cuvier, Lamarck, Say, and even our own countrymen, Dr. Leach and Montague, have all contributed, more or less, to form a ma.s.s of information which it is full time should be employed as the basis of natural cla.s.sification.

PALUDINA elongata,

_Long-spired River Snail--upper and lower figures._

_P. testa olivaceo-fusca, fasciis castaneis ornata; spira producta, attenuata, apertura multo longiore; apice acuto._