***Owo Orders.

he Levadites, or Goose-barnacles, ustangusted by a tendinous, contrace. xeu its base to some solid marine compressed shell, consisting of valves nemorane, and by having six pairs of es are usually found in places exposed to e vaves One genus appears to perfo ason. These animals roll up and a great velocity, thus creating a little eir mouth an abundant supply of ich Poli compares to fishermen cs, instead of shell, are covered by occasionally very minute shelly

Cirripedes consists of the Balanites, or are distinguished from the Lepadites a tendinous tube, the mouth of which is ... usually consisting of four valves. The

are commonly regarded as sessile; but, if a considering the valves of the shell of the gous to the operculum of the Balanites, as it their tendinous tube as really a part of the a-as its being organized, living, and muscu wave-then it must be analogous to the shelly r, and both must be considered as elevated by tabe, in the Balanites, consists usually of six sit were, together; and in several species, as acorn, of a triangular shape, and having aernately at the base and at the mouth of case of the tube generally takes the form of ch it is fixed, and is sometimes composed

448

membrane, and sometimes it is incomin this Order, has twenty-four tentacular those of the Lepadites, consisting of two pairs of large similar ones, but unequal in Net and as many smaller pairs, dissimilar and ced below. One pair of these is much larger la the water they keep these tentacles, in d thus arrest, or, by producing a current

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avorina.

2 Lithotrya.

4 Balanus Tintinnabulum. ugh called tentacles, from their use, seem rather anal other jointed organs of Condylopes.

191 to their mouth, absorb the animalcules, which constitute their ford They not only fix themselves upon inanimate substances, such as rocks, stones, the hulls of ships, &c. but also upon vanous marine animals and plants. Thus some are found on Zoophytes, as sponges and madrepores; others attached closely to each other on shell-fish, especially bivalves, so closely that the point of a pin cannot be thrust between them. One specres takes its station on the shell of the turtle;1 others plant themselves in the flesh of the seal; and others bury their tube in the unctuous blubber of the whale.

It we compare the animals of the above Orders with each other, we shall find that they are fitted by their Creator to to, eet their food in different ways. The Lepadites, by means

their long contractile flexible tube, can rise or sink, and end themselves in different directions, so as, in some sort, to pse their prey; their tentacles, also, from their greater length, seem to farther this end: these, according to Poli's met por above alluded to, they can throw out and draw in en with fry, as a fisherman does his net. When their prey is in their mouth, it is subjected to the action of their thed jaws, which seem more numerous and powerful than bose of the Balanites; and as the valves forming the shell are Ere numerous and connected by membrane, and the whole sta..¡ more compressed than the operculum of the last named atadans, we may suppose that they are capable of a more vared action, and one that may perhaps add to the momentum of the masticating organs. Hence we may conjecture that the a. mais destined to form their nutriment, may be larger, so as Le require more exertion and force, both to take and to mas

In the other Order, the structure of the Bulaniter seems to rate merely the protrusion and employment of their tentanes; and being usually attached to floating bodies, such as the halls of ships, or parasitic upon locomotive animals, riding as they do upon the back of the turtle, the dolphin, and the wha; they may visit various seas in security, and feast all the wine with little trouble and exertion, upon animalcules of ery description, the produce of arctic, temperate, and tro

With respect to their place in nature, it seems not quite clear whether they should be regarded as leading from the Moscats, with which Cuvier arranges them, towards the Crustaceans, and they certainly seem to have organs borrowed from both; their shells and mantle in some degree from one,

1 Coronula testudinaria.

plumage, and making a twittering noise when on the wing. It had a peculiar motion of the head, as if nodding to some one near it, at the same time turning itself to the right and left, and making its congé twice or thrice before its departure. This bird, he was told, was called Sucksaque, and that tradition had assigned to it the habit of entering the mouth of the crocodile, when basking in the sun, on a sand bank, for the purpose of picking what might be adhering to its teeth: which being done, upon a hint from the bird, the reptile opens his mouth and permits it to fly away.1

This seems evidently the Trochilus of Herodotus, above al luded to, as clearing the mouth of the crocodile from the leeches. Aristotle, in more than one place of his History of Animals, mentions such a bird, and a similar tradition concerning it, with that of Mr. Madox. "The Trochilus flying into the yawning mouth of the crocodile cleanses his teeth, and thus is provided with food. The latter, senisble of the benefit, suffers it to depart uninjured." In another place,3 he seems to speak of it as an aquatic bird, yet afterwards he describes it as frequenting shrubberies and subterranean places. Whether this animal really attends thus upon the crocodile has not been ascertained, but it would be singular that such a tradition should have maintained its ground so long without any foun dation.

As a farther proof that the Bdella of the father of history is a true leech, and not a mosquito,-as M. Geoffroy St. Hilaire, from the meaning of its primitive,5 would interpret the word,it may be observed that Aristotle compares the Bdella to an carth-worm, and describes its peculiar motion; and in Hesychius it is said to be a kind of Scolex or worm; Theocritus also alludes to its blood-sucking propensities.7

That leeches infest the aquatic Saurians is farther evident from a letter received by Mr. R. Taylor, and very kindly communicated by him to me, from a friend at Calcutta, Mr. W. C. Hurry, who having observed that the fauces of the gigantic cranes were generally very full of leeches, determined to examine the crocodile; and upon a large alligator he found a small red species, of which he sent specimens. A friend of mine, Mr. Martin, of Islington, observed also that the alligators

of Pulo Penang were infested, as he thought, by an animal of this kind, called by the natives its louse.

The Trochilus of Aristotle, Mr. Stanley states to Mr. Tavlor, is the Egyptian Plover; who farther observes that the Green Tly is also related to cleanse the mouths of the alligators in the West Indies, from the gnats and flies that stick, in great abundance, in the glutinous matter they contain.

But there is a terrestrial kind of leech found in the island of Ceylon, which appears to be a greater pest than any other species of the genus, and one of the greatest scourges of that the island. They infest, in immense numbers, the mountains, wds, and swampy grounds, particularly in the rainy season. They are oftener seen on leaves and stones than in the waters. The largest are about half an inch long when at rest. Their colour varies from brown, to light brown, with three longituditai yellow hnes. They are semi-transparent, and when fully exinded are like a fine chord, sharp at the extremity, and es thread any aperture, so that they can penetrate through the light clothing worn in that climate, rendering it impossible, at that season, to pass through the woods without being covered with blood. Dr. Davy counted fifty on the same person; no sor does any individual stop, than, as if they saw or scented 1. m, they crowd towards him from all quarters. From their aniense numbers, activity, and thirst of blood, they are the great pest of travellers in the interior. Percival says that the Dutch, in their march into the interior, at different times, lost several of their men from their attack. Other animals besides

v sufer dreadfully from them, and horses in particular are readored so restive, when they fasten upon them, as to be quite manageable and unsafe to ride. The only way to prevent trattak, is to cover the skin completely.

Th office devolved upon the present tribe, is one which, within certain limits, is beneficial to the animals who are the en site of it—'hough those last mentioned would be inserted en a list of the destroyers of the animal king lom-which contrite to maintain a just balance between the different memhers of it. The fly that bites the horse prevents it from over:--ing, and sɔ the leeches may be of use to the larger aquatan mds, at the same time that the smaller ones, such as the grubs of insects, must generally perish from the insertion of their sharp jaws, and the suction of their proboscis.

Yet as we see, this is one of the animals that min has taken into a lance with him, and this nɔ dɔibt Providence inten led

1 Charadrum Egyptius.

2. Tolus viridus.

lopes. They have red blood, and their circulation is by arteries and veins, but they have no special organ for the maintenance of the systole and diastole, their Creator not having given them a heart, but where the veins and the arteries meet, there is an enlargement, and the systole and diastole is more visible, as Cuvier remarks, than in the rest of the system, these enlargements therefore seem to represent a heart.

Savigny, in the third part of his Systême des Animaux sans Vertèbres divides them into five Orders, of which he gives only the characters of the four first, intending to publish, in a supplement, his account of the fifth; these Orders he arranges in two Divisions-the first including those that have bristles for locomotion, and the second those that have them not.

1. His first Order he denominates Nereideans,' and characterizes them as having legs provided with retractile subulate bristles, without claws; a distinct head with eyes and antennæ; a proboscis that can be protruded, generally armed with maxillæ.

2. The second he names Serpuleans, these add to the legs of the former retractile bristles, with claws; they have no head furnished with eyes and antennæ, and no proboscis.2

3. The third he names Lumbricinans; these have no projecting legs; but are furnished with bristles seldom retractile: they have no head with eyes and attennæ, and no maxillæ.

4. His fourth Order he names Hirudineans. They have a prehensile cavity, or sucker, at each extremity, and eyes.3

5. In his fifth Order he intends to comprehend those Annelidans that have neither bristles nor prehensile cavities, but his account of this has not been published.

He begins with the most perfect of the Annelidans, but viewing them in connexion with the worms I must reverse the order, and instead of descending ascend, which will bring me ultimately into connexion with the more distinctly jointed animals the Condylopes.

1. The Order of Hirudineans includes animals that are of the first importance, as well as some that are fearfully anoying, to mankind. The common leech' has long been so much in request with medical men, on account of the facility with which it can be applied to any part of the body where bleeding is required, that they are now become scarce in our own waters, and consequently dear, so that large numbers are imported from the Continent.

1 Nereideæ.

2 Serpulex. 3 Lumbricina and HirudineæTM 4 Hirudo medicinalis, L. (Sanguisuga, Sav.) |