:

teen such companies, one of which is always grenadiers, and posted on the right next them stand the eldest company, and on the left the second company; the youngest one being always posted in the center.

Companies not incorporated into regiments are called irregulars, or independent companies.

COMPANY of ships, a fleet of merchanmen, who make a charter party among themselves, the principal conditions whereof usually are, that certain vessels shall be acknowledged admiral, vice-admiral, and rear-admiral; that such and such signals shall be observed; that those which bear no guns shall pay so much per cent. of their cargo; and in case they be attacked, that what damages are sustained shall be reimbursed by the in general. company In the Mediterranean such companies are called Con

serves.

COMPARATIVE anatomy, is the science which examines the structure of the body in animals. It includes, in its most extensive sense, a view of the corporeal organization of all classes of the animal kingdom.

This science, which is very aptly denominated comparative anatomy, affords the most essential aid in elucidating the structure of the human body, and in explaining the doctrines of physiology.

The want of any organ in certain classes of animals, or its existence under different modifications of form, structure, &c. cannot fail to suggest most interesting conclusions concerning the office of the same part to the human subject. Thus our physiological reasonings, which must necessarily be partial and incomplete, when deduced from the structure of a single animal or class, are extended and corrected by this general comparative survey, and may therefore be relied on with the greater confidence. We are indebted to such investigations for the discovery of the circulation and of the lym. phatic system; for the elucidation of the functions of digestion and generation; indeed, there is no branch of anatomy or physiology, which has not received most material benefit from the same

source.

Hence Haller has very justly observed, that "physiology has been more illustrated by comparative anatomy, than by the dissection of the human body."

The study of comparative anatomy is moreover of the greatest importance in its

connection with veterinary science, and with that highly interesting pursuit, natural history. It would be an affront to our readers to enlarge upon its utility in the former point of view; but we may be allowed to observe on the latter subject, that anatomical structure forms the only sure basis of natural classification of the animal kingdom; and that any ar rangement, not founded on this groundwork, will lead us into the most gross and palpable errors.

ture;

Lastly, this study opens to the mind a great source of interest and satisfaction, in exhibiting such numerous and unde niable proofs of the exertion of contrivance and design in the animal strucin displaying those modifications they are adapted to the peculiar circum of particular parts and organs, by which stances of the animal, and become subservient to its wants, its necessities, or its enjoyments.

The importance of the subject, from the above-mentioned circumstances, is now so fully recognised, that it begins with justice to be considered as an essential part of a regular medical education. Public lectures have been delivered on it for some years in Germany and France; and lately the example has been followed in this metropolis.

Hitherto there has been rather a defi ciency of good works on this science, and particularly of elementary books. Blasius has given a collection of the writ ings of several authors on the anatomy of particular animals, in one volume 4to, entitled "Anatomia animalium figuris variis illustrata," Amstel. 1681; which may still be consulted with advantage, particularly on account of the plates. Cuvier's "Leçons d'Anatomie comparée," in five large 8vo. volumes, form a very valuable and useful repository of facts in comparative anatomy; but the subject is treated at such length, and with so many uninteresting details, that the book is by no means adapted for the use of students. The only compendious and scientific view of the subject, which we can recommend to beginners, is the short system published by Blumenbach of Gottingen, and translated from the German by Mr. Lawrence, who has accompanied it with

numerous additional notes.

The necessity of confining this article within a given number of pages renders it impossible for us to give a general view of the subject: we shall, therefore, select such parts as either particularly interesting in them selves, or such as become important from

are

elucidating the structure or functions of the human body.

It is necessary for us to make a few remarks on the classification of the animal kingdom, as the terms employed in the following article differ occasionally from those of the Linnæan system, which has been hitherto chiefly used in this country; and, independently of this circumstance, such of our readers, as have not particularly attended to the study of natural history, may derive assistance and information from a short sketch and explanation of the arrangement of animals according to their anatomical structure, with an enumeration of the chief genera in each order.

That the Linnæan system is exposed to numerous and well grounded objections, and that in many instances it disregards anatomical structure, which should form the basis of a natural classification, will be readily allowed by the most sanguine

admirers of its illustrious author. Yet it must be remembered, that the general adoption of this method renders it desirable to deviate from it in as few instances as possible; since the introduction of new orders and names must necessarily create difficulty and confusion in the study of the science. The French zoologists, whose successful labours in the advancement of natural history must be acknowledged with every due tribute of respect, have carried the rage of innovation too far, in the universal rejection of the Linnaan method, and the unnecessary multiplication of new orders and genera. The defects or errors of any system could not cause so much perplexity and inconvenience, as the want of a generally received standard, and the unlimited licence, in which every individual indulges, of fabricating new classifications and arrangements. To judge by some recent works, we should be led to suppose, that the merit of a systematic arrangement of animals does not consist in the simplicity or intelligibility of the system; but is in proportion to the number of newly-created terms.

Animals may be distributed into two grand divisions: those which have a vertebral column, and red blood: and those which have no vertebræ, and are white blooded.

In the former division there is always an interior skeleton; the chief support of which is the column of vertebræ, a spinal marrow contained in the vertebral canal; never more than four members, of which one or both pairs are wanting in some

instances. The brain is contained in a cranium: there is a great sympathetic nerve; five senses; two moveable eyes; and three semicircular canals in the ear. The circulation is performed by one muscular ventricle at least. There are lymphatic as well as blood vessels. The jaws being placed horizontally, the mouth is opened by their moving from above downwards, or from before backwards. There is a continuous alimentary canal, extending from the mouth to the anus, which is always placed behind the pelvis; peritoneum; liver, spleen, and pancreas; two kidneys, and renal capsules; and two testicles.

The vertebral animals are subdivided into warm and cold-blooded.

Warm blooded vertebral animals have two ventricles in the heart, and a double circulation; and breathe by means of by the brain. The eyes are closed by eyelungs. The cranium is completely filled lids. The tympanum of the ear is hollowed out of the cranium, and the labyrinth is excavated in the bone. Besides the semicircular canals, the ear has a cochlea. The nostrils communicate with the

fauces, and allow the passage of air into nished with ribs. the lungs. The trunk is constantly fur

In cold blooded vertebral animals, the brain never entirely fills the cranium. The eyes seldom possess moveable eye-lids. When the tympanum exists, it is on a level with the surface of the head. There is no cochlea. The different parts of the ear are connected but loosely to the cranium.

The division of warm blooded animals contains two classes; Mammalia and Birds.

The mammalia are viviparous, and suckle their young, from which circumstance the name is derived. They have an uterus with two cornua: and the male has a penis.

There are two occipital condyles, connecting the head to the atlas: never less than six, nor more than nine cervical vertebræ a very complicated brain; four ossicula auditus, and a spiral cochlea. The skin covered with hair. A muscular diaphragm separates the chest and abdomen. There is an epiglottis. The lower jaw only moves. The fluid in the lacteals is white, and passes through several conglobate glands. There is an

omentum.

Blumenbach establishes the following orders in this class:

I. Bimanum. Two handed.

Genus 1. Homo.

II. Quadrumana, four handed animals; having a separate thumb, capable of being opposed to the other fingers, both in their upper and lower extremities. Teeth like those of man, except that the cuspidati are generally longer.

1. Simiæ, apes, monkeys, baboons.
2. Lemur, macauco.

III. Bradypoda, slow-moving animals.

1. Bradypus, sloth.

2. Myrmecophaga, ant-eater.
3. Manis, scaly-lizard, or pangolin.
4. Dasypus or Tatu, armadillo.

This order forms two in the arrangement of Cuvier. 1st. Tardigrada; which includes the sloths. There are no incisores in either jaw; there is a complicated stomach, but no rumination. 2dly. Edentata, toothless animals. Some of these have no teeth; others want the incisores and cuspidati. The tongue is long, slender, and projectile, for seizing the insects on which the animals feed; body covered with hard substances. The armadillo, manis, ant-eater, and ornithorhyncus, or duck-billed animal, belong to this order.

IV. Cheiroptera, having the fingers elongated for the expansion of a membrane which acts as a wing.

Vespertilio, bat.

V. Glires. Rodentia of Cuvier-gnawing animals. Have two long and very large incisor teeth in each jaw, by which they cut and gnaw hard bodies, chiefly vegetables; there is a large interval behind these teeth, unoccupied by cuspidati; long intestines, and generally a large cæcum. The hind legs, being longer than the front extremities, give to these animals a leaping mode of progression. The disproportion is sometimes so great, that the front legs are not used in walking. A bone in the penis.

1. Sciurus, squirrel.

2 Glis, dormouse (Myoxus, Linn.) 3. Mus, mouse and rat. 4. Marmota, marmot. 5. Cavia, guinea-pig.

6. Lepus, hare and rabbit.

The sixth genus forms the Pedimana of the same zoologist; as they possess a separate thumb on the hind extremities only. They have a pouch in the abdomen, containing the mamma, and holding the young in their early state. One spe cies, the kanguroo, (didelphis gigantea) must however be excepted. That is placed among the rodentia, and does not possess the separate thumb.

The order carnivora of Cuvier will include from the seventh to the eleventh genus, both inclusive. These have a bone in the penis. The seal belongs to this amphibia.

In the three following orders the toes are so incased in horny coverings, that they can only serve to support the body in standing or progression. As these ani mals all feed on vegetables, the intestines are very long, and the belly consequently large.

VII. Solidungula (solipeda, Cuvier,) a single toe on each foot, with an undivid ed hoof; a small and simple stomach, but large intestines, and particularly an enor mous cæcum; incisores in both jaws; mammæ in the groin, as in the pecora.

sea,

X. Cetacea,whales, living entirely in the and formed like fishes; breathe by an opening at the top of the head, called the blowing hole; through which they throw out the water, which enters their mouth with the food; smooth skin covering a thick layer of oily fat; no external ear; a complicated stomach; multilobular kidneys; larynx of a pyramidal shape, opening towards the blowing hole; testes within the abdomen; mamma at the sides of the vulva; bones of the anterior extremity concealed and united by the skin, so as to form a kind of fin; no posterior extremi. ties; teeth which retain their prey, but do not masticate, and instead of which there are sometimes layers of a horny substance called whalebone.

4. Delphinus, dolphin, porpoise.

Cuvier distributes the class mammalia into three grand divisions:

1. Those which have claws or nails (mammiféres a ongles :) including the following orders: bimana, quadrumana, cheiroptera, plantigrada, carnivora, pedimana, rodentia, edentata, tardigrada.

2. Those which have hoofs (mammif. a ongles) including the pachydermata, ruminantia, and solipeda.

3. Those which have extremities adapted for swimming (mammif. a pieds en nageoire.) Amphibia and cetacea.

Birds are oviparous; have a single ovary and oviduct; a single occipital condyle; very numerous cervical vertebræ; a very large sternum; and anterior extremities adapted for flying, the posterior only being used for walking.

They have three eyelids; no external ear; a bone in the tongue; a cochlea conical, but not spiral; a single ossiculum auditus; body covered with feathers. The lungs are attached to the surface of the chest, and penetrated by the air, which goes all over the body; no diaphragm ; there is a larynx at each end of the trachea; no epiglottis; the jaws are covered with a horny substance, and are both moveable; there are no lips, gums, nor teeth; the chyle is transparent; no mesenteric glands, nor omentum; no bladder of urine, the ureters terminating in a bag, through which the eggs and fæces come, viz. the cloaca; the pancreas and liver have both several ducts entering the intestine; spleen in the centre of the mesentery.

This class cannot be distributed into orders so clearly distinguished by anatomical characters as the preceding one. Blumenbach divides them into two leading divisions.

(A) TERRESTRIAL BIRDS.

Order I. Accipitres. Birds of prey, with strong hooked bills, and large curved ta

Саса.

III. Pice, this and the two following or

ders are not clearly characterised.

1. Picus, woodpecker.

2. Jynx, wryneck.

3. Sitta, nuthatch.

4. Alcedo, king's-fisher.

2. Casuarius, cassowary or emu.

(B) AQUATIC BIRDS.

Order 1 Gralle, waders frequenting marshes and streams; long naked legs; long neck; cylindrical bill, of different lengths.

1. Ardea, crane, stork, heron, bit

tern.

2. Scolopax, woodcock, snipe, curlew.

3. Tringa, lapwing, hufis, and reeves.

4. Charadrius, plover.

5. Fulica, coot.

6. Rallus, rail.

7. Phænicopterus, flamingo.

8. Tantalus, ibis, &c.

II. Anseres, swimming birds; webfooted; bill broad and flat, covered by a

nerves are distributed,

1. Colymbus, diver.

2. Larus, gull.

3. Procellaria, petrel.

4. Diomedea, albatros.

5. Pelecanus, pelican, cormorant.

6. Anas, swan, duck, goose.

7. Mergus, goosander.

8. Alca, auk, puffin.

9. Aptenodytes, penguin.

The two classes of cold-blooded ver tebral animals are, the Amphibia, and

Fishes.

The former, differing considerably from each other, have very few common characters; for in different instances they walk, fly, swim, and crawl. There is no external ear, nor cochlea; the brain is always very small; the lungs are in the same cavity with the other viscera, and have very large air-cells; no epiglottis, omentum, nor mesenteric glands; two ova ries and oviducts; cloaca, through which the fæces and urine are expelled, and in which the organs of generation terminate; neither hair, feathers, nor mammæ ; skin either naked, or covered with scales; both jaws are moveable; there is an urinary bladder.

Order I. Reptilia, having four feet, (quadrupeda ovipara.)

1. Testudo, tortoise, turtle.
2. Rana, frog, toad.

3. Lacerta, lizards, crocodile, cha