All the species in

restricts the former latitude of the term. habit the sea, and frequent those situations which afford the best shelter against the violence of the waves, and the search of their enemies, usually concealing themselves in the clefts and fissures of rocks near the shore. With the tide of flood,. and especially during the night, they approach the beach, o lay hold on the marine animals which the waves have dashed against the rocks, and have thus either killed or wounded. Being aukward swimmers, and rather tardy walkers, they are often left dry, when they draw up into some retired corner, and lie as snug as they can till the return of the tide. At the moulting season they lie concealed in the crevices of rocks, at the bottom of the sea. On our shores, they are most abundant in summer, but most in season in the spring. Here we feel ourselves constrained to remark, once for all, that the respective species are passed in review with provoking brevity; a circumstance which gives an air of synoptical abstraction and dryness to the work, considered as a whole.

Dromia. Crust very protuberant; hind feet re curved on the back. The only European species is the caput mortuum, which is found in the Mediterranean, and which, as Linnê remarks, is like a human head that has been long buried. It muffles itself up in a hood, or cloak, resembling an argillaceous integument, or a bit of old leather, but which is really the alcyonium domunculus; and, shrowded in this strange disguise, it deceives both its enemies and its victims. exotic species are, artificiosa and rumphii, of which the latter is the most common in collections. It lives at the bottom of the East Indian seas, concealing itself under the sand, and skulking behind the valve of a shell, the more readily to surprize the smaller fishes.

The

Hepatus. Fore-feet notched like a cock's-comb, the exterior and palpiform pieces of the mouth having the second joint of their internal stem pointed.-Fasciatus, an inhabitant of the American seas, but whose manners are unknown, is the only species.-Calappa. Crust dilated at the posterior angles, fore-feet much notched.-Posternus. Eyes short, ar not extended to the anterior angles of the crust. Some of the species afford delicate eating.-Matula. All the feet formed for swimming. The few species belong to the warm regions of both continents. Ocypoda. Crust nearly cordate, or rhomboidal, eyes supported on a foot stalk, which extends along a large portion of the anterior margin of the crust. To this genus

belong some of the land crabs of the West Indies, of whose history many curious details may be found in Bose's Histoire Naturelle des Crustacis. Podophthalmus. Hind feet only

formed

formed for swimming, eyes very long. The spinosus, a native of the East Indies, and synonymous with Posternus vigil of Fabricius, is the only species.-Grapsus. Crust square, eyes seated in the lateral angles of the anterior margin of the crust, which is curved. Several of the species display a beautiful Tichness and variety of colouring, whence they are denominated painted; and they reside chiefly on land, in America and the West Indies. Their manners, as observed by Bosc and others, are here recorded at considerable length.-Porcellana. Hind feet by much the smallest ; exterior antenna situated behind the eyes, turned out, and very long. This is a marked and well defined genus: but the history of the few species appertaining to it is little known.-Pinnotheres. Crust nearly orbicular, internal stems of the exterior and palpiform pieces of the mouth re-united at their base.

These Crustacea are generally very small, and live within certain Bivalve shells, as muscles, cockles, &c The paguri assume the exclusive property of the univalves on which they seize but the pinnotberes keep company with the molusca, into whose habitations they intrude. It should seem that those of the muscle tribe are most liable to be visited by these troublesome guests, about the end of autumn; at least, if I rightly recollect, the Parisian venders have told me so It is commonly believed that these crustacea cause much uneasinesss to those who eat them with muscles, by inducing violent cholics. I have not examined how far this opinion is well founded: but, without absolutely denying the fact, I must confess, that I can scarcely believe it. As the flesh of the pinnotheres forms a very small mass, the substance of their crust should rather be regarded as the noxious part of them: now this substance is merely calcareous, and I cannot conceive how it should exercise any mischievous action on the coats of the stomach, or of the intestines. Yet, as we are often deceived with the finest reasonings in the world, it will be better to suspend our judgment, lest we inspire a false sense of security, and in the present instance to attend wholly to observation.'

The cause of the alarming symptoms which sometimes occur, on eating muscles, seems not hitherto to have been satisfactorily explained: but the fact is unquestioned that they sometimes do occur, and it merits the investigation of the medical faculty. The opinions of the vulgar are not always erroneous; and we see nothing absurd in the supposition that certain minute, like certain large, crabs, may be endowed with deleterious properties: in which case, the quantity of poisonous matter that acts on the system will depend on the number of these animals that are received into the stomach.

Maia. Crust triangular, and very uneven; apparent extremities of the exterior and palpiform pieces of the mouth

7

rounded;

rounded, and very obtuse. Most of the species owe their protection to the extreme roughness of their surface, by which they are confounded with the adjacent rocks or stones, especially when they lie in a contracted and tranquil state, as they usually do, on the appearance of danger.-Macropus. Crust triangular, very unequal, projecting into a snout, eyes prominent, and uncovered; exterior and palpiform pieces of the mouth elongated; feet very long, and very slender. The sea-spiders of the antients.-Leucosia. Crust ovate, inflated, and pointed; antenna scarcely apparent; exterior and palpiform pieces of the mouth very hard, with their apparent extremity tapering to a point. These are important characters, since they preclude the confusion of former systematists, arising from the singular varieties which prevail in the species; all of which, however, exhibit a peculiar form, and a bright polish. Being incapable of swimming, they keep at the bottom of the sea, and are cast on shore by the waves. When they apprehend danger, they gather their feet under their bodies, and remain stationary till it is past. They are not lively in their movements, and often escape destruction by the smallness of their size, and the hardness of their covering. To this last circumstance it is probably owing that the greatest proportion of fossil Crustacea belongs to this genus.

Corystes. Crust oval, exterior antennæ long, projecting, and approximated under the eyes; exterior and palpiform pieces of the mouth lengthened. Like some of the species of Dromia, those of this genus carry on their back extraneous bodies, such as the valves of shells, bits of fucus, sponge, coralline, &c., so as to conceal themselves from their enemies and the animals on which they subsist.Orithyia. The posterior feet are only formed for swimming. The only species is mammillaris, a native of the Chinese seas. Ranina. Fore-feet terminated by a single falciform claw; the extremities of the others formed for swimming. Pagurus. The fore-feet with two claws; the animal parasitical. To this genus belong the Hermit Crab, and others, which take possession of such empty shells as suit their dimensions, and thus at once protect the soffer parts of their crust from injury, and lie in ambush for their prey. Swammerdam, with a perversity of observation which in him was almost unaccountable, maintained that these shells were produced by the crabs which occupied them. As they increase in size, they move to a more capacious lodgement, and frequently wage furious contests for the possession of the same residence. If brought near the fire, they will crawl out APP. REV. VOL. LVI.

I i

of

of their portable habitation. The avaneiformis may often be observed, in summer, on our own shores, filing the shell of some species of Helix o. Turbo.

--

rminated by a single Te species are comthe north. Palinurus. enical joint; exterior

Albunea. Fore feet t rminated by a single claw, tarsi conical, and falciform. the manns of the two species are unknown.Hippa. Fore-feet like a simple ov piece; tarsi compressed. Sylarus. All the feet conical joint, lateral antennæ notched. mon in Barbary and Egypt, but rar in All the feet terminated by a single antennæ long, setaceous, and spinous. The anim Is belonging to this tribe affect stoney shores, and in winter resort to the mouths of rivers. They are sometimes a foot and a half long, and are in high request as an article of food at Marseilles, and along the Mediterranean. Galathea. Fore-feet terminated by two claws. This genus is nearly allied to Astacus: but M. LATREILLE has judiciously stated the points of dif ference. One of the species. which inhabits the Brazilian coast, is denominated phosphorica, from the circumstance of its shining in the dark.

Astacus. Fore-fect, and the extremities of the two following, terminated by two claws; antennæ inserted on the same line; the lateral, with a spinous peduncle, and no lateral scale; the intermediate short, and with two filaments. As this genus includes both the Lobster and the Cray-fish, which have been long familiar to observation, its illustration is extended to a considerable length, but adds little to the information which had been already acquired.-Alpheus. Differs from the preceding by the presence of a scale at the base of the peduncle of the lateral antennæ. - Penæus. Forefeet terminated by two claws, exterior antenna accompanied by a bifid and spinous scale; the intermediate inserted higher, and with two filaments. Palanion. The first two or three pair of feet terminated by two claws; intermediate antenna situated above the others, and with three filaments.-Crangen. Fore-feet terminated by a single crooked claw.

2. Branchiogastra. In this order, the first genus is Squilla, which is thus discriminated :-exterior antennæ simple, and furnished with a scale, the intermediate with three filaments; palpiform pieces of the mouth resembling feet, and terminated by a hook, or claw; three pairs of feet terminated by a simple and hairy joint. The general description of this tribe is chiefly abridged from the more ample details of de Geer.Mysis. Two simple, and two bifid antenna, the exterior furnished with a foliaceous scale; fourteen feet, terminated

by a claw. Phronima. Ten feet, those of the third pair longer, terminated by two claws; the others ending in a hook, appendages at the tail. The only known species, Sedentaria, was first noticed by Forskael, in his Fauna Arabica :"an extraordinary animal of its kind," says he, "for it inhabits a house of an extraordinary architecture, remarkable for its cubical, swoln, channelled, and gelatinous appearance, possessing a certain degree of consistency, and open at both ends. Here it remains in a bent posture, often changing its place, here it deposits its eggs, and here the young find a cradle at their birth."

Talitrus. From ten to fourteen feet; antennæ simple; the intermediate placed above the exterior, and shorter than their peduncle; tail with articulated appendages. This genus has been detached from Gammarus of Fabricius, on account of the peculiar structure and disposition of the antenne. -Gammarus. Fourteen feet; exterior antenna with a small filiform division; the intermediate placed above, and longer than the peduncle of the former; tail furnished with articulated appendages. -Caprella. Ten or twelve feet, closely paired, and extended; body filiform; no tail, nor jointed appendage at the end a genus retained from Lamarck, comprehending linearis, (Cancer Linearis Lin.,) and ventricosa. (squilla ventricosa of Muller.)-Cyamus. Feet short; those in the middle spurious, the others terminated by a claw; body large; neither tail nor jointed appendages: includes only one species, viz. ceti. (Oniscus ceti Lin.)

The new classification of the Crustacea, which we have thus rapidly sketched, is suitably illustrated by neat and accurate engravings; and it may certainly be regarded as an ingenious and elaborate attempt to facilitate our acquaintance with this department of animated nature. The impartiality of criticism, however, requires us to state that the author's provisions are more scientific than commodious, that his subject is needlessly frittered down into minute distinctions, and that his efforts have been chiefly directed to re-mould the materials of others, rather than to add to their amount.