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presenting a flat surface, as in mammalia, the body is hollowed into a funnel-shaped depression at each end, so that, by the union of one vertebra with another, a cavity is formed, consisting of two cones joined at the base; and so on, throughout the whole column. These cones, however, are not hollow, but filled with a cartilaginous substance very elastic, the structure of which appears to consist of concentric fibres, those next the centre being the softest and most pulpy. It is by means of this cartilage that the vertebræ are united, and upon it they perform all their movements; for, in another respect also, unlike those of mammalia, articular processes are wanting. This method of conjunction by intermediate cartilage, occurs only among those fishes whose skeleton is properly osseous; but in the cartilaginous order the bones of the vertebral column are so consolidated together, that they cannot be separately distinguished, except by the spinous processes.

Among osseous fishes, the cervical vertebræ are generally wanting,-in some species however they do exist, as in the herring, to the number of four. In the cartilaginous order we find them consolidated into one. The dorsal vertebræ are in general furnished with transverse processes, to which the ribs are attached, at least in the osseous order; for it is to be observed, that true ribs are wanting in the cartilaginous. Fishes have no vertebræ answering to the lumbar in mammalia; the caudal vertebræ, however, exist, to the last of which are articulated the delicate bones of the fin at its extremity.Among reptiles, the vertebral column presents very great varieties and differences.

In serpents, the skeleton itself consists of little besides the vertebræ, all of a figure nearly similar; their union is, however, very singular. The posterior articular surface of each vertebra is so constructed as to form a rounded eminence or ball, and this is received into a corresponding depression in the anterior surface of that which succeeds; thus constituting throughout the whole column a series of ball-and-socket articulations, from which the greatest flexibility is derived. The ribs are also united in a similar way to the vertebræ; that is, by means of a limited ball-and-socket articulution, the dorsal extremity of each rib having a depression, into which is received a rounded protuberance of the vertebra, The ribs in some species amount to nearly three hundred pairs. They terminate by a cartilaginous union to the scales of the belly; and according to the Count de la Cepede, in the tiger, boa, and rattlesnake, to each abdominal shield there are uni

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formly corresponding two ribs and one vertebra.

In the tortoise and turtle we find the vertebræ and ribs amalgamating with the back plate. In the lizard family, however, the vertebral column is complete, so as to admit of motion. The ribs are united to a sternum, and by their motions assist respiration. In the frog, and others of the same order, the vertebræ are cup-shaped.

Birds also depart considerably from the general plan, as we find it in mammalia. It is true, that all the vertebræ are here perfectly distinct, but all are not moveable; as for instance, the lumbar vertebræ, which are all ossified into one piece with the haunch-bones. The ribs differ also from those of mammalia. At their vertebral extremity they are bifurcated; the sternal extremity is furnished with an osseous appendix; and from the middle, a flat process projects obliquely backwards over the succeeding rib.

Before, however, we mention the ribs of animals, we ought to observe, that with the sternum (breastbone) they constitute the necessary parts of the trunk. The ribs in figure are like an arch, one extremity being united to the vertebral column, and the other attached by the cartilaginous elongations to the sternum, and thus forming in mammalia and birds the cavity of the thorar, or chest.-In some animals the ribs are wanting; in others again, as we noticed with regard to serpents, they are extremely numerous.

In the human species their number is twenty-four-twelve on each side;-but of these, seven only on each side are united to the sternum by cartilages; the remainder are short, and from the circumstance of their not uniting as the others, are termed false ribs. The sternum in man is flat and long, and forms the anterior wall of the cavity of the chest. It is connected, as we have previously stated, to the clavicles, and to fourteen of the ribs.

Its form, however, in many or most of the lower animals, exhibits considerable variety. In birds, it is of great proportionate magnitude. The internal surface is concave, while externally it is divided by a deep longitudinal ridge or crest, so that altogether it bears a rough resemblance to a boat, having a keel unusually deep. In some animals, as for instance in serpents, the sternum is wanting.

The limbs or extremities next require our consideration. In many red-blooded animals, as in serpents for instance, they are wanting in the majority, however, of this grand division, they constitute a requi

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site part of the structure; and the number when perfect is four. In all animals which possess them, they constitute the instruments of progression; and in many, of defence, or of obtaining the food which the God of nature has appointed for them.

In man, the inferior extremities alone are used in progression; these comprehend the legs and feet; the anterior extremities, viz. the arms and hands, at once place man at the head of the animal kingdom. Man uses the hand not merely for grasping or retaining, but for examining many of the properties of the natural objects around him, thus making it an agent to intellect an apparatus for increasing knowledge of adding to the stock of ideas-of informing or correcting the judgment.

In quadrupeds, the extremities are not distinguished by the terms which are appropriate only to those of man,-but are divided into fore and hind legs. In birds, the extremities are wings and legs; in fishes, pectoral and ventral fins. In the whale the posterior extremities cannot be distinguished from the tail, which serves as an organ of progression and defence.

If we examine the limbs of all animals, we find that they are not only adapted to the wants of the species, but that they correspond naturally with the design and mechanism of the system. There is, as we have before observed, a mutual relationship, an harmonious coincidence, between all parts of the organic frame; and this concordance is beautifully exemplified in the relation which obtains between the formation of the extremities, and the construction and arrangement of the teeth, involving consequently the structure and power of the stomach and digestive apparatus, the relative perfection or development of various muscles,--in short, the total mechanism of the whole machine; while, in like manner, the construction of any part of the system reciprocally manifests that of the limbs also,

For example, to elucidate our meaning, let us take a carnivorous animal, (say the tiger,) and examine the structure and mechanism of the paw. Fashioned as it is, and armed with tremendous claws, we see at a glance its fitness for striking down and lacerating the stag or ox, on whose flesh it preys. This fact being then ascertained, another in connexion immediately presents itself, namely, that the teeth must also be adapted for cutting and dividing it. This construction of the teeth supposes a relative figure and strength of jaw, and muscles of a certain power for moving it. The condyles, or articulating eminences, must also be con

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structed accordingly, and the hollows or depressions of the bones of the skull, in which the muscles of the jaws are situated, will have their peculiar depth and charac ter. The organization of the stomach will also be in accordance; and every part of the system will harmonize; we shall see a power of frame for pursuing and overcome ing the prey, and organs of sense modified for discovering it even at a distance; while in the brain nature has placed that instinct which impels it to lie in ambush, and watch patiently the moment to dart upon its victim. Now, vice versa, a tooth, or the condyle of the jaw, will give in like manner the form of the paw or foot, the figure of the scapula, the nature of the food, and the general plan of the whole.

Such are the general conditions. But subordinate to these, there are others having a

relation not only to the nature of the food, but the manner of obtaining it; determined for instance, by the size, the spe cies, or the haunts of the animals upon which the individual is adapted to prey, and hence result modifications of detail in the forms, the grand outline of which arises from these general conditions. Thus the class, the order, the genus, and species, have each their diagnostics in an equally harmonious concordance, so that to the comparative anatomist, a tooth, or the seapula, or the foot, is a key to the certain determination of the order and genus, and even the species, to which the fragment shall have belonged.

This harmony, not only of the bones of the skeleton, but of the whole organic economy, according to the broad view thus stated, is simple; and the fitness and design of this relationship of parts are at once obvious. There are, however, relations of forms, of which, from their constant and unvarying concurrence, experience and observation alone inform us, but for which we are unable to assign an adequate reason, although we may be well assured, that wisdom has not planned them in vain, Thus, for example, we may well conceive that hoofed animals must necessarily be all herbivorous, since they have no means of seizing upon prey; and reasoning onwards, we may expect to find the teeth flattened, and adapted for grinding or bruising herbs, or seeds; we may also expect a relative form of the condyle of the jaw, and its articulating cavity, permitting the requisite freedom of lateral motion. We may likewise suppose, that the muscles of the jaws will not need such bold depressions that the shoulder-blades, instead of being expanded and strong for powerful muscles,

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will be narrow

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and-socket, there being no occasion to turn the fore-arm. In general also, we may conceive the necessity of a more complicated system of digestive organs; but it is by observation alone, that we ascertain the fact, that animals only which ruminate have true cloven hoofs, and that all ruminating animals have them; that in this class alone there are horns on the forehead-except where the canine teeth are developed-and that where this is the case, the feet manifest a greater relationship to those of non-ruminant animals, having the number of bones in the feet increased, the fibula (small bone of the leg,) more distinct from the tibia; or both circumstances conjoined. If we examine the camel and the musk deer, we see examples at once in point. In the latter, in which the canine teeth are greatly developed, the fibula and tibia are perfectly distinct; whereas in other cloven-footed animals the fibula is wanting, there being merely a small bone articulated at the lower end of the tibia. In the camel, which has canine teeth, as well as two or four incisor teeth in the upper jaw, there is an additional bone in the tarsus, with small hoofs and phalanges. In the cow, on the other hand, and in the sheep and deer, there are no incisors in the upper jaw, the gum being merely indurated, the two metacarpal and metatarsal bones are united, to form what are called the canon bones, and the forehead (in the males, at least in a state of nature,) is furnished with horns.

first adjacent to the fore-arm, the second to the bones of the metacarpus; each row will consist of four bones; but the fourth of the first row seems in a manner out of its rank. On each bone there are several cartilaginous surfaces for their mutual articulations, and on some for articulating with the radius, the bones of the metacarpus, and first bone of the thumb.

The names of the bones of the carpus are as follows: In the first row, the first is the os scaphoides or naviculare, the second the os lunare, the third the os cuneiforme, (from its occupying the situation of a wedge,) the fourth the os orbiculare or pisiforme, and which may be easily felt on the outer edge, next the fore-arm on the concave side. In the second row, the first is the os trapezium, the second the trapezoides, the third the os magnum, the fourth the os unciforme. The bones of the carpus support those of the metacarpus; these consist of four long bones in each hand, upon which rest the fingers; externally they are slightly convex, but the internal surface is flattened and concave. They are not in contact throughout their whole length, but only at the extremities, where an enlargement takes place, and where they are knit together by ligaments. The bones of the thumb and fingers, which in man are all perfectly distinct and elaborately fashioned, are termed by anatomists the phalanges, from a fancied similarity in arrangement to the Greek páλays; the number in each hand is fif

teen.

Of these, the first row of the fingers is attached to the extremities of the four metacarpal bones; but the first bone of the thumb is attached to the carpus, and the mechanism is such as to enable the thumb to exert an opposing action to that of the fingers, thus producing that facility of grasp

ties in man.

The bones of the anterior extremity consist of the clavicle and scapula which form the shoulder-the humerus (or arm bone,) the ulna and radius (bones of the fore-arm,) all of which we have noticed before,-and the bones of the hand. The hand is united to the radius, by which it gains the two motions, pronation and supination; and its bones are divided into the carpal, the metacarpal, and the phalanges. The carpal bones in each hand are eight in number, and their shape is irregular; in their natural arrangement they present externally, that is, on the outer side of the hand, a surface convex, even, and regular, but internally a concavity more rugged, having

characteristic.

Hammersmith.

W. MARTIN.

(To be continued.)

ASTRONOMICAL OCCURRENCES FOR

MARCH, 1829.

MARS is still a conspicuous object in the western hemisphere; he is observed in the evening of the 1st under the three first stars of the Ram, approaching a line drawn from a Arietis to Mencar, in the head of the Whale. At the same instant Saturn is noticed in the constellation Cancer, which is situated in the eastern hemisphere; he is very slowly approaching a line drawn from Castor through Pollux, and produced.

the same day, the sun completes his journey through the constellations and signs of the zodiac, as he enters the equinoctial sign Aries at this time, after a lapse of 365 days, 5 hours, and 50 minutes. This is consequently the commencement of the spring quarter, and on this day the duration of the Sun above our horizon, and also of every other on the surface of the globe, is exactly 12 hours: the Sun has no declination on this day, in consequence of his being vertical to the equinoctial line; his semi-diameter is 16 minutes, 4 seconds, and 5 tenths, and it passes the meridian in 1 minute, 4 seconds, and 3-tenths; his hourly motion in space is 2 minutes, 28 seconds, and 8-tenths. The Moon is noticed after passing the syzygy to approach the noble planet Jupiter, now considerably to the east of her; the first satellite of this vast orb disappears in his shadow, on the morning of the 25th, at 51 minutes 10 seconds past 2. On the following morning the Moon is noticed considerably nearer this planet, and will pass him before her next appearance, the conjunction taking place at 45 minutes past 3 in the afternoon. On the 27th, Mercury arrives at his greatest western elongation, and may probably be noticed by the skilful observer in the morning, a little before sun-rise, as his distance from the great luminary of the solar system is upwards of 27 degrees; the time that has elapsed since his eastern elongation is 43 days, and since his western 116 days; from this statement, it appears that the planet has been longer travelling from his western to eastern elongation, than from his eastern to western, which is a decisive proof of the ellipticity of his orbit. Saturn is stationary on the 28th, in 27 degrees 24 minutes of Cancer: he now commences a direct motion, after moving retrograde for the space of 133 days.

At 19 minutes past 7 in the morning of this day, the Moon enters her last quarter in the 7th degree of Aries; the time elapsed from the full is 7 days, 17 hours, and 28 minutes, which is 7 hours, 37 minutes less than the same period in February, and is occasioned by the line of the apside forming a greater angle with that of the syzygies; the period from the first quarter, being half of the orbit, is 15 days, 21 hours, and 30 minutes, which is 3 hours 27 minutes less than the preceding period between the same points of her orbit, and 2 days, 8 hours, and 1 minute more than her motion from her last quarter to her first; or, in other words, she is longer by the above period in describing the higher part of

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her orbit: her synodical revolution from this point is completed in 29 days, 16 hours, and 59 minutes, which is 4 hours less than her preceding one. Mercury is in aphelio on the following day, 88 days having elapsed since he was in a similar position. On the 31st, Jupiter is stationary in 15 degrees 16 minutes of Sagittarius; he now commences a retrograde motion, after moving direct during a period of 262 days.

P. S. The following statement in the last Occur

rences are erroneous.

Col. 139, line 27, for "22" read "10".-Col.140, line 6 from bottom, for "longest," read “shortest."-Line 4, for "shortest," read "longest. - Ditto for "first quarters," read "full Moons."-Line 3, for "10 and 34," read "8 and 19."

LIFE INSURANCE.

THIS science is nearly perfected, though its principles and facts are not generally known, even among subscribers. A mutual insurance may be instituted thirty per cent under the public offices, and without capital. It is sufficient that a banker is employed to receive the yearly premium, and pay the money insured, receiving certificates of health and death.

The just scale is this: A person in health, aged twenty years, engaging not to leave Europe, or enter Italy, Greece, or Turkey, should pay thirty shillings a year, to have the power of bequeathing one hundred pounds, to be paid at his death. A scale for other ages from ten to sixty years is made by the rule of proportion, founded on the probable duration of life, ascertained by tables and registers of insurance. The person twenty years old is likely to live thirty-three years, that is, half the dif ference between his age and EIGHTY-SIX (this eighty-six is a number found by data or documents.) A man of forty is calcu lated to live, perhaps, twenty-three years, on the same foundation, 86-40=46 half 23. A child of ten may be accounted to have thirty-eight years further life. Thus, ten from eighty-six leaves seventy-six, the half of which is thirty-eight. The profession should be considered, some being doubly hazardous-colliers, miners, copper smelters, &c.

A prudential society will not insure very large sums to individuals, because it is ascertained, that insurance spread over a large surface, does not fluctuate in risk more than one-seventh the number of deaths, one year more or less than another There is no use in limiting insurance to those who have an interest depending. It is enough that a man insures his own life, or the life of one who consents to it.