ART. VII. Records of the Results of Dredging. No. 3., Including Notices of Species of Naticida. By EDWARD FORBES, Esq.

Two species of Nática occur on the Manx coast; namely, N. monilifera Lam. (the Nática glaúcina of British authors) and N. rufa Mont. The former is very frequent, the latter rare: they are found on gravelly bottoms, at a depth of from 12 to 20 fathoms of water. I have examined the animals of both, and do not recollect having met with any description of them in print as the results are interesting, and perhaps important, I shall state them here.

24

f

Nática monilifera Lam.: a, a side view of the extracted animal; b, a front view, the tentacular hood and mantle reflected; c, a front view of the head; d, a view of the head from beneath, showing the foot-like process; e, one of the cartilaginous jaws; f, the operculum. The figures are all larger than the parts that they represent.

The head of the N. monilífera resembles a produced tubercle, is of a pink colour, and presents, in front, a pearshaped opening, placed vertically, which is the mouth. From the centre of the mouth slightly protrudes the anterior part of the jaws, with the apex of the tongue between them. These jaws are cartilaginous, of a square form and considerable size, toothed in front like a saw. The tongue resembles that of a Littorina [VIII. 75.], but is shorter and broader in proportion. Beneath the head, and attached to it only, is a process resembling a little foot. The mantle is pinkish white, and presents nothing remarkable in its form: beneath it is a sort of hood, produced at one side into a broad triangular tentaculum, which is pinkish white at the base, and brown towards the apex, but presenting no appearance of an eye. I have examined six animals, and never found more than one tentaculum. The foot is dilated; of a pinkish white colour, with the sides variegated with brown. The operculum is thin, corneous, and of a pale brownish yellow colour.

The animal of N. rùfa is white, with the exception of a fine thread-like line of dark brown, which borders the much dilated foot. It has no eyes, and is furnished with two lan

ceolate white tentacula, which, when the animal is at rest, are reflexed on the shell, along with the edge of the hood. The shell varies in wanting one of the white bands, which are described as encircling it spirally.

It will be seen from these descriptions that our British Náticæ differ materially, in regard to the inhabitants of the shells, from the generic characters of Lamarck and Rang, who describe the animal as furnished with two tentacula, very long and sharp, bearing on their outer sides sessile eyes.

In the seventeenth volume of the Linnæan Transactions is an important paper by that most observant naturalist, Lansdown Guilding, on the family " Natícidæ Guild.," in which he divides the Lamarckian genus Nática into two; namely, Nática and Naticina, characterising the latter from the Ñ. mammílla, and some other West Indian species, the animals of which he found eyeless, and differing from the animal of Lamarck in many other particulars, corresponding nearly with the descriptions I have given above, which were drawn up before I had seen his paper. He, however, describes the mouth as "subtus cartilagineum, proboscidiforme, intra caput retractilium." [Cartilaginous beneath, proboscis-shaped, retractile into the head.] May he not have mistaken the small foot-like process beneath the head for a proboscis, to which it has, indeed, a great resemblance?

It would be very desirable to ascertain whether all the Natícida with corneous opercula are blind, and whether all those with testaceous opercula accord with the descriptions of Lamarck and Rang.

Should my observation on the tentacula in this genus prove correct, it might induce us to ask the physiological question, Does the absence of eyes degrade the number of tentacula from a generic to a specific character?

I have my doubts as to the identity with N. monilífera of what are placed as large British specimens of that species: they appear to me more nearly allied to N. rùfa. An examination of the animal would settle that point. I have never obtained these shells when dredging: they are said to occur buried in the sand, at very low tides, in the Frith of Forth.

The N. nítida of Donovan is generally described as being white my specimens have all brownish bands on a white ground. It appears to inhabit shallower water than either N. monilifera or rùfa, and my friend Dr. Knapp informs me it is not uncommon at St. Andrews. I have not as yet seen the animal.

The N. pallidula and lacuna of Fleming form the genus Lacuna of Turton; which may constitute a very excellent

subgenus of Littorina, as the animals are generically allied. The animal of L. pallidula is white, with two long white tentacula; the eyes at the external base.

All the true British Nática may be referred to the genus Naticina of Guilding, unless the N. tuberosíssima of Laskey be an exception. The N. canrèna is but doubtfully native. They may be arranged thus:-Genus, Naticina Guilding: Species 1. monilifera Lam., synonyme, glaúcina Mont., not of Lin.; 2. rùfa Mont.; 3. nítida Donov.; 4. glabríssima Brown, synon. sulcàta Turt.; 5. helicöìdes Johnston, in Trans. of Berwickshire Nat. Club, 1835; ?6., tuberosíssima Mont. Appendix, the fry of the larger species: N. pellucida and álba of Adams.

In describing the animal of the N. monilífera, I have incidentally referred to its tongue. This is an organ on which I am inclined to bestow more importance, in relation to generic character, than has hitherto been ascribed to it. Its form, length, texture, the shape of the expansions at its extremity, and the direction and form of the hooks with which it is provided, are all characters deserving of attention, and constant in resemblance amongst the several species of each genus, especially amongst the holostomatous tribes of Pulmonibránchia, as well as the Scutibránchia and Cyclobránchia. By the way, I should feel rather inclined to question the statement that the tongue in the Mollúsca is worn away at its apex by use. (See an interesting essay on the digestive organs of Mollusca in this Magazine, the Number for February, 1835.) [VIII. 71-80.] Independent of the somewhat unscientific nature of the supposition, the structure of the end of the tongue would seem to forbid such an idea, especially the constant and precise form of the membranous expansions at the extremity.

6. Howe Street, Edinburgh, Jan. 1836.

[Desultory Notes by the late Rev. Lansdown Guilding, relative to Notices in Vols. I. and II. of this Magazine, on certain Molluscous and Aquatic Kinds of Animals.]

I. 102. The Species of Animals which discharge a coloured or acrid Fluid are much more numerous than most Persons suppose. The whole of the Laplýsiæ and the Iánthina slowly pour forth a fluid of the most splendid purple, which serves to darken the surrounding water, and confuse their pursuers. In the Púrpuræ the fluid is, at first, of milky whiteness, and only by degrees acquires its lovely tints. Other marine beings eject a colourless and pungent secretion, which drives their enemies to a distance. I have seen the Portuguese man

де

of war (Physàlia pelagica), so common in the calms of the Atlantic Ocean, repel several large fish, which, with a violent splashing and eager motion, were endeavouring to seize and devour it, but were constantly overcome by the stinging particles which nature has given for the protection of this soft, defenceless, and splendid animal. The Cephalopoda have the power of ejecting their coloured secretion to some distance. I was lately in search of shells, wading, with a friend, on a reef, who was much terrified at being suddenly covered from head to foot with the inky discharge of a captured Sèpia.

II. 24. Many of our floating Marine Animals are highly poisonous to the Skin. I have known a soldier in the neighbouring garrison suffer dreadfully while bathing with the troops. I saw the man's arm, in the hospital, much swollen and inflamed. The torture he endured was very great, and did not cease for several days.

The Cuttle Fish, or, as they are here called, sea cats, do not in our seas attain to any formidable size. They are sometimes eaten. They are very quick in their motions: indeed, it is a difficult task to secure them without a spear, so quickly do they hobble away under the rocks.

The Motion of most free Bivalves is moderately slow, and interrupted, and the protruded foot is principally used. I have to describe a new genus, closely allied to Lìma Sowerby, which is locomotive, and swims (by opening and closing the valves, and the action of the numerous large tentacula with which the margins of the cloak are fringed) with as much ease as a fish. The collector, indeed, in deep water, without a drag net, would have no little trouble to secure it.

I. 198. This gelatinous and offensive Substance was, doubtless, of animal origin, though it might be difficult to ascertain what produced it. The sea is sometimes covered to a vast extent with a subgelatinous, brownish, floating scum, which may prove to be the ova of marine creatures. The larger Gorgònia, on the death of their aggregate Pólypi, are sometimes covered with a gelatinous coat, exceedingly difficult to remove. The air scarcely dries it; and, if moistened by rain, it is quickly restored: boiling alone seems to remove it altogether. The jelly seems to be highly acrid. On a late dredging expedition, my hands were so completely poisoned from fishing up Gorgòniæ, from the spicula of marine bodies, and the brittle spines of a kind of Ophiùra, that for many days I could not dress myself. The cuticle of my fingers fell off, and their natural sensation was not for a long time restored.

I. 487. The slimy Secretion of the Pólypi of Corals and Gorgònia is certainly acrid, and often painfully irritating to the skin. They form, too, a slippery and treacherous footing. When walking among dangerous rocks, covered for many yards with these aggregate creatures, and other Radiata, I have sometimes narrowly escaped serious falls.

I. 355. The Mollusca, though destitute of a Skeleton, fashion their Shells with more Correctness than the writer imagines. Monsters and varieties will occasionally occur, and shells, in their infancy, will present the aspect of genera to which their inhabitants are not even remotely allied: but their thinness and unfinished whorls easily point out their imperfect condition, without leading conchologists into the [case supposed in I. 355.].

I. 495. Búlla lignària. See Humphrey, Linnæan Transactions, ii. p. 15. tab. 2. Other shells [shelled molluscous animals] have the gizzard-like organ, as your correspondent will see in the paper pointed out to him, which was written by one of the most active collectors of his day.

II. 69. The Spinning Slug is a distinct species, well described in the Linnæan Transactions, and beautifully figured in the princely work of my friend the Baron de Férussac. In the Virgin Islands there is a common species of Cyclóstoma, which, having given out a mucous thread, closes the operculum, and swings by the thread when hardened by the air. The creature is thus safe from ants and other enemies.

II. 102. The account alluded to of the structure and habits of the Naútilus and Tròchus is fabulous and absurd. II. 73. This Astèrias seems to have been engraved from a rude sketch. It bears a great resemblance to a species common in the Caribean seas. Dele "& b, a section of a small

bivalve shell."

II. 154. I doubt the fact of star fish destroying oysters. I. 62. Erratum. - For "Polybrachìone," read "Polybrachiònia." -[Lansdown Guilding. St. Vincent, May 1. 1830.]

ART. VIII.

Views on the Uses of the Nectary and Corolla in Plants. By Mr. WILLIAM GARDINER, Jun.

It is with much diffidence that I submit to your readers the following remarks on the uses of the corolla and nectary in the vegetable economy, these remarks being derived solely from observation; while I believe that correct experiments,