of the Pterocerata, MM. Quoy and Gaimard think it may belong to generation. The heart is elongated, very delicate, and attached upon the rectum at the part where it begins to form a loop. It has two auricles, one anterior and the other posterior, to receive the blood from each gill.

The mouth is a fleshy mass, ovoïd, and provided with protractor and retractor muscles, with a horny bifid plate at its aperture, and with a rather long and wide tongue furnished with strong hooks. As in Parmophorus, the oesophagus contains four long, membranous, and very villous folds. Its salivary glands form but a moderate bundle placed below.

The tract of the oesophagus is rather long before it enters the liver, where, partially, is placed the stomach, which last is very ample, globular, and divided, as it were, into two compartments internally: the cardiac portion is smooth, folded longitudinally; the pyloric covered with linear granulations, converging towards the aperture. A little farther on, the intestine forms many close-set circumvolutions, whence issues the great loop which terminates by the rectum.

The liver is enormous, and composes of itself nearly the whole of the spiral portion of the animal (tortillon), embracing, as has already been observed, a portion of the stomach and intestine into which it pours the bile. It did not appear to MM. Quoy and Gaimard to be easily divisible into lobes. It is covered by an organ consisting of a delicate layer, ordinarily of a different colour, most frequently of a pale yellow, which MM. Quoy and Gaimard suppose to belong to generation. Perhaps, they observe, one might look for the analogue of a penis in the spirallyrolled body seen on the left side of the liver. But though MM. Quoy and Gaimard avow that they have not been able to follow out the relations of this spiral with the. uterus or its appendages, they are certain that it has no reference to the tongue.

The nervous system, they observe, differs from that of the other mollusks, in having the upper ring placed very near the mouth, and the lower more backward below the cesophagus. They remark that one may easily overlook it, and take another loop for it, especially in Haliotis. Ganglionary points of this nervous circle give off filaments for all parts of the body.

The colour of the foot is grass-green on the sides, slightly brown above, and of a beautiful yellow below; the head is red-brown and striated, with a narrow green band at the base of the eyes and the palmettes. These four appendages are bordered with green, as well as the muzzle, which is striated with brown. The tentacles and the edge of the lateral fringe of the feet are green also. The contour of the mantle is yellow, and the operculum white (we may add, externally, for on the inside it is chestnut).

The anatomy of this Turbo is given in the atlas of the Astrolabe (Zoologie, pl. 59, f. 10).

Living specimens were brought to the Astrolabe at Amboyna, and there only, by the Malays; and MM. Quoy and Gaimard could not obtain any account of the habits of this species. They add that the inhabitants of Vagiou probably eat it, for they often found the shells of this Turbo empty upon the heap of other molluscous shells, from which the natives obtain food. (Astrolabe.)

The number of living species of Turbo, recorded by M. Deshayes in his tables, is fifty-six. Examples.-Turbo marmoratus. Description.-Animal (see above).

Shell subovate, very ventricose, imperforate, smooth, green marbled with white and brown or subfasciated; the last whorl transversely nodulous in a triple series, the upper nodules greatest; the lip at the base flattened into a short subreflected tail-like process; mouth silvery. This shell when deprived of its external layer exhibits a silvery, iridescent, and very brilliant nacre.

Turbo torquatus.

Description.-Shell orbiculate-convex, broadly and deeply umbilicated, transversely sulcated, substriated with close-set longitudinal lamellæ of a grey-green colour; whorls above, coronated; the last girt with a median carina; spire blunt at the apex. (Lam.)

MM. Quoy and Gaimard state that the foot of this Turbo often takes a quadrilateral form, but it can elongate itself into a trumpet-shape, as they have represented it: it is yellow below, dotted with red-brown on the lateral parts.

Turbo marmoratus.

a, View of back; b, view of month with the operculum in; c, inside of oper culum.

The mouth is under an enlarged hood, which is notched, greenish, and striated below, striped with red-brown above. The tentacles, moderately long for the size of the animal. are yellowish, annulated with brown. They carry the eyes at their base upon a fringed pedicle. The palmettes are equally laciniated. The lateral fringes of the foot have only a single yellowish filament. The parts contained in the spire are also yellowish, après la cuisson. The oval operculum is remarkable for its doubly spiral guillochure of a fine white, and granulated.

The shell, when deprived of its first layer, is beautifully nacreous.

This species, which grows to a large size, inhabits King George's Sound. Only a few individuals were found alive. Turbo Cookii.

Description.-Shell orbiculate-convex, with a ventricose dilated base, longitudinally plicate, rough, rufo-fuscescent; the plications very frequent, close-set, oblique, imbricato-squamous; the whorls convex; lower surface rather convex, concentrically rugous, and imperforate. (Lam.)

The animal has long, filiform, white tentacles, dotted with red-brown, without palmettes at their internal part; the eyes pediculated. The mouth is elongated in form of a proboscis, or is widened into a hood. It is white, striated

transversely with black. The foot is large, yellowish, dotted with brown below, with a median line of the same colour.

The operculum is oval, rounded at one of its extremities with an oblong fosset, sometimes paucispiral. It is white and greenish. Its spiral is less pronounced than in the greater portion of the other Turbines.

Locality.-MM. Quoy and Gaimard found this species in great numbers in Tasman's Bay, New Zealand, in the Bight of the Astrolabe (l'Anse de l'Astrolabe), and on the reefs of the Passe des Français. They add that one may judge of its small degree of locomotion from the dirty incrustation, so difficult to be removed, with which the shell is covered. It grows to considerable size. (Astrolabe.)

The number of living species above noticed is below the mark, and in all probability does not include the species described by Sowerby and others. (Müller's Synopsis.) Turbo has been found at depths ranging from the surface to ten fathoms, on rocks and weeds.

M. Deshayes gives thirty-four as the number of fossil species (tertiary), and of these Turbo rugosus, a new species, and T. costatus, are stated to be found both living and fossil (tertiary). Among the Fossil Shells from the Western Borders of the Red Sea, communicated by Mr. Greenough to Mr. Lyell, Turbines chrysostomus and petholatus are noticed. Turbines naticoides, nitens, and lineata, appear in Mr. Lea's list of new tertiary fossils from Claiborne, Alabama (Contributions to Geology). The genus occurs also in the strata below the chalk. Five species are enumerated by Mr. Murchison from the Silurian rocks.

The number of living species of Monodonta given by M. Deshayes in his tables is forty-two, and eight are recorded as fossil (tertiary). Monodonta Pharaonis is noted as occurring in more than one tertiary formation. Among the

Turbo Cookii.

a, Shell; b, shell seen from below, animal nearly in profile; c, anterior part of animal seen from below; d, inside of operculum; e, outside. (Astrolabe.) Recent Monodontæ have been found generally on rocks and weeds.

The number of species of Littorina given by M. Deshayes in his tables is twenty-four, and ten are recorded as fossil (tertiary). Littorine littorea and striata are noted as found both living and fossil (tertiary).

Littorina occurs also below the chalk. Dr. Fitton, for instance, records seven species in his Stratigraphical List. Most of these are from the lower green-sand, but one is from the Portland stone, and another from the Oxford oolite. Mr. Murchison records a species from the Silurian rocks (Caradoc limestone).

Recent Littorina (the common periwinkle is an example) are generally found on rocks and weeds near and

on the shore. Littorina pulchra has been found on mangrove-trees fourteen feet above the water. They have also been kept alive six months without water. See the Zoology of the Astrolabe for descriptions and figures of many species. [PERIWINKLE.]

Phasianella.

MM. Quoy and Gaimard express their opinion that the Phasianella are true Turbines in all the forms of their organization, and that they ought only to form a division in the genus.

These shells, they observe, once so rare, began to be of less value in consequence of Baudin's voyage, and that of the Astrolabe has rendered them common. The place probably most frequented by them is, according to these zoologists, Port Western in Bass's Strait. They cover the sandy beaches of this vast tract. Each tide carries these mollusks to the shore, where they live high and dry for some hours, and endeavour to withdraw themselves from the heat of the sun by hiding under the fuci. Under such shelter they congregate so numerously that seventy-six were found under one of these plants.

The Phasianella, observe the same zoologists, are always smooth. This polish, and, still more, their continual movements, prevent them from being covered with Serpule, Flustre, and other parasites which encrust sluggish shells. This agitation makes it difficult for them to preserve the contour of their aperture perfect, for it is very frail. In millions of individuals MM. Quoy and Gaimard always found the lip trenchant, never thick or with a border.

The species appeared to them very difficult to characterise, both with regard to the animal and the shell. The last especially presents so much diversity of colour, and sometimes of form, that one may be deceived, and advance simple varieties to the rank of species. MM. Quoy and Gaimard saw some of these shells, which were brown and greenish during life, become red after death by the solar action, &c.

The most common tint of these mollusks is stated by them to be brown dotted with greenish. This colour is proper to those whose shells are nearly of a similar hue; whilst those which approach white or are speckled with red have the animal of a grass-green.

These are lively active animals, and voracious withal, for they were taken in nets baited with flesh let down into the sea. Their foot, endowed with great mobility, is elongated like a proboscis: its great peculiarity is its faculty of moving in two portions as it were, that is to say, each of its sides advances separately and successively; and a longitudinal gutter may be perceived on its lower surface.

On the coasts of New Holland, the Phasianella found at King George's Sound are larger and less numerous than at Port Western. They are few in number on the coasts of Van Diemen's Land. The operculum is always cal

careous.

Example.-Phasianella bulimoides.

Description.-Shell oblong-conical, smooth, pale yellow, transversely banded; the bands frequent and diversely variegated and spotted; spire acute at the apex.

The animals are generally of a fine green nearly throughout. One will have more white dots on the foot, and another a violet or reddish spot on the lateral fringes of the foot; a third will have this organ yellowish and slightly fringed upon the borders. In all the tentacles are slender and long, the ocular peduncles stout and button-shaped, the palmettes laciniated. The muzzle, which is elongated a little in the form of a proboscis not retractile, can also modify itself into the shape of a rounded scutcheon (écusson). The fringes of the sides of the feet are very finely laciniated, and sometimes present brown ramifications of vessels; they carry three greenish filaments on each side.

The operculum is oval, calcareous, slightly convex, white, and covered for a portion of its contour by a fleshy lamina of the foot which supports it.

Locality. Very common at Port Western, being the species above alluded to, and larger at King George's Sound. MM. Quoy and Gaimard observe, that Lamarck indicates it as coming from New Zealand: this, they remark, is possible, but they never found any traces of Phasianell there.

The animals above described came from King George's Sound,

Phasianella bulimoides.

a, animal and shell seen from below; b, the same seen from above; c, shell; d, operculum. (Astrolabe.)

The number of species enumerated by M. Deshayes in his tables amounts to nine living and four fossil (tertiary Of these Phasianella pullus is noted as recent and fossil (tertiary).

Phasianella occurs also below the chalk. Dr. Fitton records three species, all from Blackdown, for example. Here we may notice the genus Tuba of Lea, which that acute zoologist thus defines:

Shell conical, umbilicate; whorls rounded; mouth round; margin not united above; columella thickened and reflected at the base.

This genus,' says Mr. Lea, is nearly allied to Turbo and to the RISSOA of Freminville; but not being able, with propriety, to place it with either, I propose to constitute for it a new genus. The reflected margin, which is dis posed to be effuse, has at the base some similarity to the Melania, and therefore cannot be placed in the genus Turbo. It cannot be placed in the genus Rissoa, being umbilicated. In eight species of Rissoa in my cabinet, all are thickened round the margin, forming a varix. The Tuba has no thickening of this kind, the margin being crenulate. The Rissoa has an acute apex, while that of the Tuba is almost truncate, the superior whorls being smooth and gibbous. Mr. Sowerby's "Mineral Conchology," plate 395, figures a shell (Turbo sculptus), which, think, should be placed in this genus. It is from the London clay of Barton. Of it, and the preceding one, he says, they do not agree precisely with the character of the genus Turbo of Lamarck;" and further, "they form a passage towards Delphinula." Mr. Lea enumerates three

I

66

We proceed to the consideration of the genera Nerita, Navicella, and Natica, which, though they cannot be said to belong to the Turbinida, especially the lastnamed genus, which we shall find to be very peculiar, are yet so far analogous to the forms which compose that family, that they may as well find a place here. Nerita, Linn.

Linnæus placed the genus Nerita between Helix and Haliotis, and he divided the genus into the following sec

tions:

* Umbilicata. Species: canrena, glaucina, vitellus, albumen, mammillata.

** Imperforate, with a toothless lip. Species: corona, radula, cornea, fluviatilis, littoralis, and lacustris.

*** Imperforate, with a toothed lip. Species: pulligera, pupa, bidens, viridis, virginea, polita, peloronta, albicila, histrio, plicata, grossa, chamaLeon, undata, and exuvia.

We find then that in the Systema Natura Linnæus made no marked distinction between the marine and freshwater Nerits.

The Neritacea of Lamarck comprise the genera Navicella, Neritina (Freshwater Nerits), Nerita (Marine Nerits), Natica, and JANTHINA.

Cuvier makes the Nerites (Nerita, Linn.) immediately follow the Janthines, and includes under them Natica, Lam.; the Nerits, properly so called (Nerita, Lam.; Peloronta, Oken); Velates, Montf. (Nerita perversa, Gmel., a large fossil species); Neritina, Lam. and Clithon, Montf. (the crowned Neritines).

M. de Blainville's Hemicyclostomata, equivalent to Nerita, Linn., comprise the genera Natica, Nerita, and Naricella, or, as he terms it, Septaria.

Nerita he divides into the following sections :—

* Right lip toothed. (Genus Nerita, Lam.)

M. Rang adopts the arrangement of M. de Blainville, and condemns Lamarck for generically separating the marine and freshwater Nerits. M. Rang says that there are many species of fossil Nerits.

Mr. Swainson places the family Naticide between his Turbida and Trochide, making it consist of the following subfamilies and genera. His arrangement is, he says, founded on the shells only, from ignorance of the animals of the major part :

Subfam. 1. Naticinæ. Sea-Snails. Genera: Natica, Lam. (with the subgenera Naticella, Globularia, Mamillaria, Sigaretus, Naticaria, Lacuna, Leucotis). Subfam.? Neritinæ. Nerits.

Genera: Nerita, Linn. (with the subgenus Neritopsis, Gray); Neritina, Lam. (with the subgenera Clithon, Velotes (Velates), Pileolus, and Navicella). (Malacology.) Mr. J. E. Gray makes the Neritida the sixth family of his Podophthalma, and places it between the Fissurellida and the Ampullariada. Mr. Gray's Neritidae comprise the following genera:-Nerita, Pileolus, Culana, Neritina, Clithon, Dostia, Velates, and Navicella.

(Genus Peloronta, Öken.)

Example, Nerita peloronta.

B. Species with two teeth.

Example, Nerita exuvia.

C. Species with three or fourth teeth.

Example, Nerita lineata.

** The right lip not toothed. (Genus Neritina, Lam.) D. Species less thick, with the right lip trenchant, and the operculum very oblique. (Genus Neritina, Lam.) Example, Neritina fluviatilis.

E. Species whose columellar lip is toothed, and which are provided with spines. Example, Nerita corona.

F. Species with the columellar lip toothed; the two extremities of the right lip prolonged much beyond the aperture, and forming, with the callosity which covers the columellar lip, a sort of auricles produced by the tentacular lobe of the animal. Example, Nerita auriculata.

G. Calyptroïd species, with the upper summit vertical and spired; the last whorl forming the whole base of the shell, and occupied below by a large callosity, which sometimes covers the whole spire. (Genus Velates, Montf.)

Example, Nerita perversa.

H. Patelloïd species, which are elongated, non-symmetrical, with a dorsal summit, and not spired. (Genus Pileolus, Sow.) Example, Nerita altavillensis.

M. de Blainville observes that this genus is formed of marine and fluviatile species, which led Lamarck to subdivide it into two genera, according to the thickness of the Shell, which is greatest in the first, and the denticles on the right lip, which are entirely null in the second. M. de Blainville's observations lead him to the conclusion that the Species are still more easily distinguished by the sculpture quillochis) of the external surface of the operculum than by any other character. He remarks that Lamarck enuerates seventeen species of Marine Nerits, which are all from the equatorial and southern seas, and twenty-one River Nerits, or Neritine, two of which only are European and the others belonging to America and Asia.

M. de Blainville states that only two fossil Nerits are

comparatively thick shell, which is very rarely furnished with an epidermis, are always found in the sea; and the Neritina of Lamarck, whose shell is more delicate and almost constantly covered with an epidermis, are always. inhabitants of fresh-water: a single instance of one of these Neritine having wandered into the sea, they may, they say, perhaps have had to cite. The Nerits have a particular and distinctive appearance: they pass a part of their life out of the water without ever removing to a distance from it. Those which haunt streams or marshes may adhere to the leaves of trees, but without going on land. Those which are found on land are carried there by Paguri or by some accident. Marine Nerits are also seen at the mouth of rivers; and MM. Quoy and Gaimard remark that these are transitions which nearly all the mollusks undergo without suffering much.

MM. Quoy and Gaimard state that they were sometimes astonished to see these animals bear, upon the black rocks, all the action of an equatorial sun without appearing to be affected by it. They owe this faculty to providing, when they adhere, some drops of water which sufficiently refresh their branchiæ. This store, or what is left of it, they discharge when they are lifted from the rock.

The Nerits are very widely spread in warm climates. They are gregarious, and many species are found grouped on the same rock. Some love sheltered nooks, others are exposed to the fury of the waves; and, among those which haunt fresh-waters, some live in the deeps in the midst of the strongest currents; others, on the contrary, keep themselves in the slime of marshes. In their sufficiently agile movements their lips are constantly observed in motion.

The animal has a large head, a little notched in front, with two rounded lobes on the sides. The aperture of the mouth, which is subjacent to this sort of hood, is wide and plicated. The tentacles are always very long, pointed, and soft, carrying the eyes at their base upon a pedicle. The foot is oval, narrowed, a little pointed behind, wide in front, with a marginal furrow, and sometimes a depression, which gives it the appearance of being slightly lobated.

The edges of the mantle are fringed, so as to correspond with the internal furrows of the shell. There is no siphon. The pulmonary cavity is proportionally very large; a single, long, triangular, and pointed gill traverses it from

left to right. It is free at its extremity. Its lamellæ appeared double to MM. Quoy and Gaimard. The heart is simple, placed backwards and to the left; its ventricle embraces the end of the intestinal loop, which has the appearance of traversing it.

To the right of this cavity, and in the female, is a group of organs worthy of attention. There are seen, first, the extremity of the rectum, and then a very elongated pyriform body, surrounded partially by a sort of gland which is striated transversely, and which opens below. This organ is hollow, and contains within its cavity, coadapted to each other, many bodies in an elongated mass, terminating in filaments. They are of a resisting substance, fibrous as it were, and appear granulated under a magnifying lens. The particular use of this little apparatus MM. Quoy and Gaimard cannot divine, but they think it doubtless fulfils some functions relative to generation, for it is only found in females. More externally is the uterus, composed of a pyriform pouch, and of a renflement which is coadapted to it, which contained a great quantity of round, white, and cretaceous eggs. The large, long, and tortuous oviduct causes this organ to communicate with the ovary, which is placed at the right border of the liver.

In the male the testicle occupies the same place. The deferent canal is knotted upon it; it is a thread, which in water may be unravelled to the length of two feet. It becomes stouter at its termination, which MM. Quoy and Gaimard traced to the exciting organ, which last is short, and placed at the base of the right tentacle.

The mouth, of which something has been already said, is an oval mass, sustained by two small articulated cartilages, and covered with muscles. Above is inserted a rather long riband with five rows of hooks. The sophagus is slender, as well as the stomach, which is hardly distinguishable from the rest of the intestinal canal. This last, after having passed into the liver, returns to the buccal enlargement, thus describing a great circle, and touches the heart, which is applied upon it at the base of the gill, and terminates by the rectum. Two great salivary glands, which are flat and granulated, and shortly pediculated, repose upon the oesophagus without adhering to it. Their duct passes under the brain. The liver appears to be formed of a single mass describing an elbowlike figure (coude), from left to right, and lodging in a cavity of the shell, the commencement of the spire, which returns forward and is placed under the dentilations of the aperture of the shell.

The cerebral ganglion forms a triangular loop in which the oesophagus passes. The branches unite below in two small ganglions, which touch each other. From it are given off nervous filaments for the different parts of the body. (Astrolabe).

Example.-Nerita polita.

Description.-Shell thick, smooth, somewhat shining, longitudinally striated very finely, varying in colour; the spire very retuse, the lip toothed, smooth above. (Lam.)

This species, according to MM. Quoy and Gaimard, is the most plentifully diffused of any of the genus, and is found in nearly all the seas of warm climates. It is heavy, polished, marbled, and often coloured with three red transverse bands.

The animal is of a uniform yellowish white, with the exception of the tentacles, which are of a smoky-brown colour.

This shell is deeply striated, rugous, yellowish-grey, with circumscribed brown spots upon the parts in relief; aperture smooth, yellowish-white; peristome dotted with white and brown.

The animal has the foot yellow below, striated and dotted with deep brown on the sides, so as to appear nearly black on a yellowish ground. The head, which has a very expanded hood, is striated in the same manner. The neck is violet. The tentacles are long, pointed, livelybrown, striated longitudinally with black. The eyes placed at their base, are at the extremity of a triangular palette of yellowish-white, having a black stripe at the external border. The mantle has its contour dotted with brown. The operculum is red-brown, very much granulated, angular at the posterior border, and provided with a very projecting heel or process.

Locality. The Island of Ascension. (Astrolabe.)

Nerita Ascensionis.

a, shell with animal; b, operculum.

Nerita (Neritina) pulligera.

Description.-Shell ovate, slightly striated, blackishbrown; the outer lip dilated, thin, white within, the margin acute, the inner border yellowish; the inner lip toothed. (Lam.)

This fine species is uniform chestnut, with the striæ of growth strongly marked; these converge on the spire, which is covered by the right lip.

The animal has long delicate tentacles, which are yel lowish soiled with brown. The head and sides of the foot are yellow, spotted with brown and black. The under part of the foot is reddish.

The operculum is large, of an apple-green colour, with black transverse bands proceeding to converge towards the spire: its contour has a reddish line. (Astrolabe.)

The drawing from which MM. Quoy and Gaimard have figured this species was made at Umata in the island of Guam. They state that there are also Nertiæ pulligere a Vanikoro. They found on the trees dead shells whose

Nerita (Neritina) pulligera. a, shell and animal; b, operculum.

spire was always corroded, and they inquire whether they had been brought there, or whether the animal had died after having ascended the trees. They state as a remarkable fact, that in a great number of individuals of this species they found in the liver a small knot of worms, some of which were not less than seventeen lines in length. They were pointed at both ends, like Lumbrici, or Round

worms.

The number of species of Nerita recorded by M. Deshayes in his tables is 18 living and 16 fossil (tertiary). The genus is noted in the list of Red Sea fossil shells above alluded to. It occurs also below the chalk. Dr. Fitton, in his Stratigraphical Table, notices two species with a? from the Portland stone, and Mr. Murchison records one, positively, from the Silurian rocks (Wenlock limestone and Wenlock shale).

Deshayes is GG living and 17 fossil (tertiary); of these N The number of species of Neritina noticed by M. Auviatilis is recorded as both living and fossil (tertiary.