Zoological Illustrations Volume Ii Part 16

_Testa globosa, umbilicata. Spira depressa vel brevissima. Apertura integra, magna, ovata. Operculum testaceum vel corneum. Animal fluviatile._

Sh.e.l.l globose, umbilicated. Spire depressed or very short. Aperture entire, large, oval. Operculum sh.e.l.ly or h.o.r.n.y. Animal fluviatile.--Generic Type _Helix ampullacea_ Lin.

SPECIFIC CHARACTER.

_A. testa ovato-globosa, olivacea, fasciis obscuro-purpureis angustis ornata; spira brevi, levata, apice acuto; labii margine tenui; umbilico mediocri._

Sh.e.l.l ovate-globose, olive, with narrow bands of obscure purple; spire short, elevated, the tip acute; margin of the lip thin; umbilicus moderate.

Am. fasciata. _En. Meth._ _pl._ 457. _f._ 3. _f._ 4. (_reversed and young_).

Helix ampullacea. _Linn. Lister_, 130. _f._ 30. _Seba_, _t._ 38. _f._ 1 _to_ 6, 58, 59. _Chemnitz_, 9. _t._ 128. _f._ 1135. _Gualt._ _t._ 1. R.

In the selection of generic characters, sufficiently important to separate Ampullaria from Paludina, great difficulty at present exists; as the fundamental principle on which they should be founded (the formation of the animal) is entirely wanting. It is only known that these sh.e.l.ls, like the Paludinae, are furnished with an operculum. The absence or presence of this organ has been found of the first generic importance; though the substance of which it is composed, as well as the form it a.s.sumes, can be considered only as indicating specific distinctions. This is proved from the fact, that among the Naticae some have h.o.r.n.y, and some sh.e.l.ly, opercula: in Phasianella, this part is, in some species, almost flat, in others remarkably convex; in _Turbo, Lam._ its form is even more variable, and in the present genus a similar uncertainty exists. One species alone has been positively described as having this part sh.e.l.ly, while in two others the operculum is as certainly known to be h.o.r.n.y; to these last may be added a third, found by myself in the lakes of Pernambuco in Brazil, but to which I have not immediate access. The sh.e.l.ls here figured were, however, received from the same place by Mrs. Mawe, and, I think, are of the identical species. The spire is sometimes worn, and the whole sh.e.l.l very thin.

Several fossil sh.e.l.ls of this genus are mentioned as existing in the extinct volcanoes of Ronca, in bituminous marl near Pont St. Esprit, &c. as quoted (on the authority of the ill.u.s.trious Cuvier) by Mr. Bowdich.

Pl. 104

[Ill.u.s.tration]

NATICA punctata,

_Spotted Natica._

GENERIC CHARACTER.--See Pl. 75.

SPECIFIC CHARACTER.

_N. testa ovato-globosa, cra.s.sa, alba, strigis undatis punctisque castaneis ornata; umbilico magno, aperto, simplici; columellae basi obsoleta._

Sh.e.l.l ovate-globose, thick, white with waved stripes and minute chesnut dots; umbilicus large, open, simple; base of the pillar obsolete.

Nerita punctata. _Martini_ 11. _pl._ 197. _f._ 1903 _and_ 4. _Seba_, _pl._ 38. _f._ 33? _Gualt._ _pl._ 67. _f._ _M. and T._ (_good._)

Gochet. _Adanson Sen._ _pl._ 13. _f._ 4.

The undulated brown lines in this sh.e.l.l, are sometimes broken into three irregular bands of either lines or spots, between which are numerous minute dots; in other varieties these dots are only round the suture, and in some totally wanting. Its most constant character rests on the umbilicus, which is rather large, very deep, and without any appearance of the base of the pillar. The mouth is also more contracted than usual. It is said by Adanson to be common on the coast of Senegal; and this observing naturalist adds, that the operculum is testaceous, of a pure white, and marked with numerous concentric grooves at the upper angle.

NATICA effusa.

_N. testa depressa, alba, maculis castaneis ornata; spira brevissima; columellae basi cra.s.sa, plana, ad labium interius sinu annexa._

Sh.e.l.l depressed, white, with chesnut spots; spire very small; umbilicus large, open, spreading; base of the pillar thick, flat, and united to the inner lip by a sinus.

In form, and sometimes in colour, this sh.e.l.l bears a close resemblance to the oval variety of N. mamilla (_Nerita mamilla Lin._); but, the umbilicus, instead of being entirely closed up, is remarkably open, very deep, and the pillar forming an elevated ridge within; colour in the sh.e.l.ls of this genus is a very secondary, and, in many cases, a most fallacious guide for the discrimination of the species; for this is sometimes pure white, and I have specimens of _N. mamilla_ entirely orange. This is a rare sh.e.l.l, probably from India.

Pl. 105

[Ill.u.s.tration]

TROCHILUS recurvirostris,

_Recurved-bill Humming Bird._

GENERIC CHARACTER.--See Pl. 82.

SPECIFIC CHARACTER.

_T. aureo-viridis, jugulo smaragdino; pectore medio corporeque nigris; rectricibus lateralibus subtus topazinis; rostro recurvo._

Golden green; throat shining emerald green; middle of the breast and body black; lateral tail feathers beneath topazine; bill recurved.

The extraordinary formation in the bill of this beautiful little creature, is without parallel in any land bird yet discovered, and presents in miniature a striking resemblance to that of the Avoset. It is almost impossible to conjecture rightly the use of this singular formation; but it appears to me not very improbable, that the princ.i.p.al sustenance of the bird may be drawn from the pendent _Bignoniae_, and other similar plants, so common in South America, whose corollae are long, and generally bent in their tube; the nectar, being at the bottom, could not be reached either by a straight or incurved bill, though very easily by one corresponding to the shape of the flower.

The figure is the size of life. Bill black, depressed along the whole length, but more especially at the tip, which is rounded, thin, obtuse, and recurved in both mandibles; the under of which, towards the middle, has a convex swelling, which gives the recurvature a stronger appearance. All the upper plumage and body beneath golden-green; the throat, to the breast, shining with scale-like feathers of a vivid emerald-green. From the breast to the vent is a stripe of black down the middle; thighs white; tail even, the two middle feathers dull greenish-blue, the rest above obscure coppery-brown, but beneath of a rich shining topaz colour.

I believe this bird is _unique_; I purchased it at Mr. Bullock's sale, and that gentleman received it from Peru. It presents so much of the genuine habit of the _Trochili_, that I have retained it under that genus; for, though the bill is differently formed, that exception does not point out any important difference from the general economy of those birds.