elevated above the head, and as long as the body, bifid at the apex, and with an internal branch near the base; behind this is another shorter blunt horn, with a branch on each side; the scutélfum near the end is also armed with a short blunt horn. The tégmina and wings are veined longitudinally. Country. Choco, in Colombia. b a Centròtus Hardwickii. (fig. 5. b)—Body four and a half lines long, brownish-black, sprinkled with short, decumbent, inconspicuous hairs; legs, except the thighs, paler than the rest of the body; thorax minutely punctate, elevated above the head into a recurved quadrangular horn rather shorter than the body, and terminating in a fork resembling a pair of concavo-convex pedunculated pointed leaves; scutéllum length of the body, punctate, acute, and elevated into a rounded lobe near the apex. Tégmina naked, punctate, veined longitudinally. f. 8. Country. Nepal, in the East Indies. Centrotus cruciatus Fab. (fig. 5. c) Stoll's Cigales, pl. 2. a Centròtus globulàris Fab. (fig. 6. a) Stoll's Cigales, pl. 28. f. 163. :· Centròtus marginàtus Fab. (fig. 6. b) Stoll's Cigales, pl. 11. f. 53. Centròtus cláviger Fab. (fig.6. c) Stoll's Cigales, pl. 21. f. 115. WILLIAM KIRBY. ART. VI. The Natural History of Molluscous Animals. Sir, Letter 1. Introduction. I AM not surprised at the pleasure you express having received from the sight of the rich cabinet of Lady Conchylia. Shells, from the ease with which they can be preserved, from their elegance and beauty, have, at all times, been favourite objects with collectors; and as show was in general the main object, so various methods were devised to heighten their gloss, and unveil their hidden colours. Much of the effect produced by Her Ladyship's splendid specimens is the result of these artifices: but this childish amusement has gradually given way to a more rational pursuit; and while shells are collected with greater eagerness than ever, it is with the view of unfolding a page in the volume of creation; of enlarging our knowledge of the structure and functions of animated beings; of satisfying a blameless curiosity concerning the habits and purposes of creatures whom their Author has pronounced to be all "very good;" of improving our taste by the contemplation of the most beautiful and elegant forms; and for the very interesting end of illustrating the structure of the earth, and chronicling its revolutions. Naturalists, however, have now agreed that shells form no isolated class of natural objects; but that there are many animals destitute of a shell, which yet cannot be disjoined from them without the grossest violation of nature. These, then, we must not omit; and, instead of the "History of Shells" you request, I shall attempt to give you that of the MOLLU'SCA, the name by which this class is now designated. Molluscous animals have no internal articulated bones, nor are their bodies divided into segments by any external fissures. They are soft and fleshy; either naked, or, more commonly, covered with a shell of one or more pieces. They have no legs nor articulated members of any kind; and they either crawl on the earth, or swim in the water, by means of extended portions of their skin, which can rarely claim a title to be called fins. The cuttle-fish and slug are examples which will give you a general notion of the naked tribes; and with the great variety in the shelled species you are now familiar. At the first glance, you might suppose that such creatures can be productive neither of much benefit nor much injury to man; but a little detail will convince you that this would be a hasty conclusion. The catalogue of their " injuries," I must acknowledge, is not extensive. The slug (Limax) and snail (Hèlix horténsis) (fig. 7. a), the gardener will inform you, frequently destroy, and perhaps always more or less injure, his early crops, while they mutilate and render disgusting the fruits of autumn: but the farmer often finds them a more serious pest; for in spring they often issue, in inconceivable numbers, from their concealments on a dewy eve, and feed upon the young and tender crops. No kind of herbage seems unpalatable to them, but to clovers they give a preference; and the damage they annually do to them and to turnips is really very great. Many fields were this summer made barren by them, and more were so thinned as to require to be resown. Of the marine tribes the Terèdo navàlis (fig. 7. b), or Shipworm, is the only one which has excited notice by its destructive powers. This shell-enclosed worm, which Linnæus has emphatically, yet not undeservedly, styled the "calamitas navium," is said to have been introduced into our seas from the East within little more than a century. They are now common in all the seas of Europe; and being gifted with the power of perforating wood, they have done, and continue to do, extensive mischief to ships, piers, and all submarine wooden buildings. The soundest and hardest oak cannot resist them; but, in the course of four or five years, they will so drill it, as to render its removal necessary, as has happened in the dockyard of Plymouth. In the years 1731 and 1732, the United Provinces were under a dreadful alarm, for it was discovered that these worms had made such depredations on the piles which support the banks of Zealand, as to threaten them with total destruction, and to claim from man what he had wrested from the ocean. Fortunately they, a few years after, totally abandoned that island, from causes unknown, but suspected to be "from their not being able to live in that latitude when the winter was rather severer than usual." But still they might return; and so a prize of value was offered to any one who should discover a remedy against their attacks. What answer was returned I am ignorant; but the method now adopted to preserve the timbers necessarily used about the docks at Plymouth is, to cover that part which is continually under water with short broad-headed nails, which, in salt water, soon cover every part with a strong coating of rust, impenetrable to these animals. You may think it rather ridiculous to speak of the direct injuries such sluggish creatures, doomed to creep on the earth or crawl in the waters, can inflict: and they are, in truth, a harmless race, none of them being armed with any weapon of offence; yet, even from amongst them, has man sought the means of aiding his vile purposes. The sea-hare, the Lèpus marinus of the ancients, familiar to classical readers, and once famous in the annals of superstition, is a member of this class. Modern naturalists call it Aphýsia depìlans. (fig. 7. c) It is a snail-like animal, of a purplish-brown colour, common on our own shores, which, at pleasure, discharges from under its cloak large quantities of a fluid of the richest purple colour, This creature, it was once believed, held such antipathy to man, that the mere touch of it would cause the hair to fall of, and the sight of it was sufficient to subdue the obstinacy of concealed pregnancy. That such an animal should supply a potent poison is not wonderful; and accordingly we are told that Nero mixed it with the food of those inimical to him, and that with this poison Titus was despatched by Domitian. Its operation was speedy, and inevitable destruction the effect: yet it was not often used, as it was believed to betray itself by some peculiar symptoms. (See Beckman's Hist. of Inventions, vol. i. p. 82.) And yet it is curious that, notwithstanding all this has been said by very grave men, and very gravely too, modern naturalists have proved it to be perfectly harmless, neither offensive to the smell, nor poisonous to the touch. Some shell-fish, however, are really poisonous when eaten. This is frequently the case with muscles (Mýtilus edulis). I have known them to produce an itchy eruption and swelling over the whole body, attended with great anxiety and con siderable fever. On some parts of the Yorkshire coast they are considered poisonous, and in consequence never eaten; and several cases are on record in which their use proved fatal. Some of Captain Vancouver's men having breakfasted on roasted muscles, were soon after seized with a numbness about their faces and extremities; their whole bodies were shortly affected in the same manner, attended with sickness and giddiness, and one died. In the month of June, 1827, a great number of the poor in Leith were poisoned by eating these shellfish, which they procured from the docks. "The town," says Dr. Combe, "was in a ferment, and the magistrates, with great propriety, issued a warning against the use of the muscles. Many deaths were reported, and hundreds of individuals were stated to be suffering under it. Luckily, matters were not so deplorable; but we ascertained that, in addition to the man mentioned before, the companion of our patient, an elderly woman, had died. In all, about thirty cases occurred, with great uniformity of symptoms, but varying very much in severity; but none, so far as I know, have left any permanent bad effects." To what cause these deleterious effects are to be ascribed is uncertain; for muscles, you are aware, may commonly be eaten with impunity. Some attribute them to disease in the fish, or to its being in a state of putrefaction; others to its having fed on some poisonous articles, more particularly on the ores of copper; and others, again, to the peculiar idiosyncrasies of the sufferers. In many cases this latter explanation will suffice; but sometimes, as in the Leith cases, it is obviously insufficient. The disease of the fish has never been satisfactorily ascertained: they are eaten fresh and alive, and cannot, of course, be putrid; while the most delicate chemical tests give no indications of cupreous impregnation. Upon the whole, the effects seem to be best explained by attributing them to a peculiar poison generated in the fish, under unknown circumstances; an opinion adopted by those medical men who have attended most to the subject. Now list! One of the Mollúsca actually doth attack man vi et armis. I must beg you will, like a good-natured hero of Mr. Crabbe's, dispose yourself" wonders to believe," and be ready to grant "That things improbable may still be true." "A friend of mine," says Mr. Pennant, when speaking of a kind of cuttle-fish (Octopus vulgàris), "long resident among the Indian isles, and a diligent observer of nature, informed me that the natives affirm that some have been seen two fathoms broad over their centre, and each arm nine fathoms long. |