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5. Of the charges of Public Instruction.-It has always Deen a question in political economy, whether the public were interested in the cultivation of the sciences, and, if so, whether it ought to be at the expense of teaching

them?

Every advance of science is succeeded by an increase of social happiness, for man is necessarily dependent on the fixed laws of nature for his subsistence. The better those laws are understood, the better will be his situation. The superiority of enlightened over barbarous nations, in wealth and influence, are sufficient proofs of this fact, and the immense growth of America in so short a space of time may and ought to be attributed in a great degree to the universality of its educational system. The public are undoubtedly interested in the mental cultivation of all its citizens.

6. Of the charges of Public Benevolent Institutions. Individual distress has no title to public relief, except when it is a necessary consequence of the existing institutions of society, and only then when it can be shown that the social system itself affords no means of prevention or cure. Institutions of the kind, however, exist, and are, in fact, kinds of social banks to which every one contributes a portion of his income, that he, himself, may claim a benefit in case of accident or misfortune. Some of these establishments are supported by their power of production, and when their product exceeds their outlay, they are no longer charges upon society. This, however, rarely occurs. The principal benefit they do society is the fact, that they partially relieve the poorer classes from supporting the aged and infirm, and thereby allow population to increase more rapidly than it otherwise would.

7. Of the charges of Public Works.-These are generally heavy, consisting of rent, of the interest of the capital employed in their erection, and of the annual charge for their maintenance. Some of these items may be curtailed-rent, for instance, or the charges of maintenance when they are at all productive. Roads and canals are - costly examples even under the most judicious management; but the business facilities they afford society fully compensate for their cost. Public works of no real utility are only items of national luxury, and are as indefensible as private prodigality. They never compensate for the loss or the misery they often occasion.

OF THE ACTUAL CONTRIBUTORS TO PUBLIC CONSUMPTION.

Sometimes a portion of the objects of public consumption are furnished by private individuals, but the mass of the resources of a government are drawn directly or indirectly from its people. The government, however, from the sale of public lands, or by leasing them, and thus forming a revenue for its own support, may maintain itself in part; it can never do so entirely. Neither is it right that it should, for it is but fair that the people of a nation should pay for the protection, tranquillity, and safety they enjoy, both in person and property, under a well-balanced administration. The products thus obtained are generally taxes, the nature of which we shall consider hereafter.

OF TAXATION.

Taxation, as has been seen, is the transfer of a portion of the products of a people from their hands to those of the government. Its object is to provide funds. The name of the tax is unimportant, for whether it be called an aid, custom, subsidy, or gift, it is still a burden imposed on the people, considered as individuals, by the government for the purpose of supplying the consumption it may think proper to direct at their expense.

The object of taxation is not the commodity, but its value. Its being paid in coin, goods or personal service is an accidental circumstance more or less advantageous, as the case may be, to the government or the individual. The essential point is the value, which, the moment it leaves the tax-payer, is lost to him, and when it leaves the hands of the government is lost to the world eternally. Taxation serves to deprive the payer either of the gratification he might have in consuming his product, or of preventing its increase, for that part which is lost cannot produce to him again. Taxation, of course, then, tends to lessen, instead of increasing the wealth of a nation, and when pushed to an extreme, impoverishes the individual without enriching a state. History furnishes thousands of examples of this fact.

The best kinds of taxes are, 1. Those which are most moderate in their ratio; 2. Such as are attended with the fewest vexatious circumstances; 3. Such as fall equally on all classes; 4. Such as do the least injury to production; and, 5. Such as are most favourable to the formation of a healthy national morality.

Taxation is either direct or indirect-direct when a specific portion of an individual's revenue is absolutely demanded; or indirect when the demand is made for a specific sum on each act of consumption of any object to which individual revenue may be applied. The latter is the easiest collected and least felt.

Taxation in kind is the specific appropriation of a portion of the gross product to the public service.

OF NATIONAL DEBT.

The distinction between an individual borrower and a government in the same situation is this, that the first seeks for capital for the sake of beneficial employment, and the latter for barren consumption and expenditure. A nation rarely borrows except to satisfy some unexpected demand, or to meet some equally unexpected emergency. The loan in either case may prove effectual or otherwise. At any rate, the whole sum borrowed is so much value lost to the world, while the national revenue continues burdened with the interest yearly accruing on it.

National loans of all kinds are attended with the disadvantage of converting capital, which would otherwise be employed in production, into a means of barren consumption, and in countries where the credit of the government is low, of elevating considerably the interest of capital. Public prosperity can never be advanced by borrowing, except where the capital, so obtained, is em ployed in safe and certain modes of successful productior. which can rarely if ever be the case.

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ZOOLOGY.

THE branch of Natural History termed ZOOLOGY, is that which treats of the beings composing the Animal Kingdom. The general aspect of these, and the characters by which they may be ordinarily distinguished from plants, are under the observation of every one, and they need not here, therefore, be dwelt upon. It is only when we descend the scale, and arrive at the lowest and simplest of each kingdom, that the characters upon which we have been accustomed to rely successively disappear, and we meet with several tribes which it is very difficult to assign with certainty to either natural division. Thus, there are many animalcules in which no structure characteristic of the Animal Kingdom can be discovered; and yet they exhibit an activity of motion, evidently influenced by the sensations they experience, which shows them to be far removed from plants. It is when the characteristic structure of animals, and the manifestations of sensibility and power of spontaneous movement disappear together, as is the case in the sponge, that the naturalist is the most perplexed in regard to the place he shall assign to such beings; and he can only solve the question, by ascertaining whether the general resemblance is the greatest to beings of distinctly animal or of distinctly vegetable character. By this criterion, the sponge will hereafter be found to deserve a place in the Animal Kingdom.

The differences of structure which are most universally found to separate animals from plants, are those which are connected with the mode in which food is assimilated (or converted into the materials of their own fabric) by the beings of the two kingdoms respectively. Thus, it may be constantly noticed that plants imbibe their nourishment either through their external surface or by prolongations of this into roots and leaves. On the other hand, animals nearly always possess an internal cavity, the stomach, into which the food is received, and where it undergoes a preparation; and the absorption of it into the system takes place by vessels distributed on the walls of this cavity. Plants require nothing but a regular supply of water, with carbonic acid, ammonia, and a small quantity of saline matter dissolved in it; and the conditions of their growth generally afford them a constant supply of these, which they can imbibe by means of their roots and leaves, without moving from the place in which they are once fixed. But animals

can only be supported by materials previously organized, all their food being derived from vegetable or animal substances; this is nearly always in a solid state, and has to be reduced to a fluid form in order to be imbibed into the tissues.

The life of every animal presents a number of facts for observation; and these may be separated from each other according to their character. Thus, we might consider their structure only-the department of science which is termed anatomy. Or we might examine their actions or functions-in fact, the history of their liveswhich is termed physiology. In pursuing either of these, however, we might restrict our inquiries to a single animal, though it would not be advantageous to do so. The objects of the zoologist are different. He sees that the several beings included in the Animal Kingdom may be regarded not only in their individual aspect, but in their relations to each other; that they form parts of one vast plan, as harmonious in itself as that of a beautiful building made up of a vast number of subordinate parts; and that, while the diversities of form and aspect seem almost infinite, they are evidently subordinate to certain general principles, which produce not only the manifest conformity, but the apparent departures from it. The grand aim of the scientific zoologist being to discover this plan, he employs classification as a means by which to facilitate his acquaintance with the vast number of beings that claim his attention.

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CLASSIFICATION.

On looking at the variety of animal forms around us such as we are familiar with as inhabitants of this country, or as natives of other climates collected for our observation-the mind naturally associates together those which have the greatest general resemblance, and separates these (although differing in some degree among themselves) from those with which they have greater dissimilarity. It is by pursuing this plan, from one stage or degree of resemblance and difference to another, that classifications are formed; and these will be correct according to the amount of knowledge upon which they are founded, respecting not only the external form but the internal structure of the objects they include.

Experience teaches that the offspring of any kind of animal is similar to its parents, though slight variations may be often traced between them; but a succession of beings having this general conformity is called a race. Now, the first object which the naturalist has to determine is, whether two races, such as the Negro and European races of man, or any two breeds of dogs, might have had a common origin. If he finds reason to believe that their differences are not greater than may be accounted for by the influence of accidental causes, and especially if he finds one race ever producing the form of another, he considers them as springing originally from a common stock, and as of one species; but if he cannot thus account for their differences, he regards them as of different species. This division of all the existing forms of animals into species is that on which the naturalist has to found all his subsequent classification; and it is necessary to take great care to avoid errors arising from variations in the forms of animals at different periods of their existence.

A number of species, differing from each other in trivial points, but having a strong general resemblance, are said to belong to one genus. The genera mbst

ZOOLOGY.

nearly allied are united into one family; several families into an order; and several orders into a class. The class, therefore, contains a very large number of species, many of them differing widely from each other, but all agreeing in some prominent and important character. And the classes composing the Animal Kingdom are arranged under four groups, on account of their correspondence in certain general particulars, and their difference in others: these are called sub-kingdoms. This is the alphabet of the science; and when this has been acquired, the student will proceed to his grammar, which consists of such a knowledge of the principal divisions of the animal kingdom, as will enable him to read the language of nature with understanding, so as to learn from the simple name much respecting the structure and character of the particular specimen, of which he would otherwise be ignorant.

PRIMARY DIVISIONS OF THE ANIMAL KINGDOM.

In considering the primary subdivisions of the Animal Kingdom, it is desirable to view them at first in their most simple aspect, and to regard merely the points of agreement among all the beings contained in each group, and their most striking differences from the members of other groups. The subordinate differences among the forms contained in any one of the primary groups, will be subsequently attended to. Following the arrangement of Cuvier, which in this respect is unexceptionable, we divide the animal kingdom into four subkingdoms-VERTEBRATA, ARTICULATA, MOLLUSCA, and RADIATA. The principal characteristics of these will now be pointed out.

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The

with two jaws, which are placed one above or before the
other; there are never more than two, and they never open
sideways as in the Articulata. They are usually armed
with teeth, which are in structure very analogous to bone.
The Vertebrata are characterized by a higher degree of
intelligence than is possessed by any other group.
animal powers of sensibility and spontaneous motion are
also greatly developed; and in accordance with these, a
complete symmetry or correspondence between the two
sides of the body is observable externally. But this sym
metry does not extend to the organs of vegetative life,
which are irregularly disposed in the cavities which they
occupy.

In the ARTICULATA, the skeleton is external, envelop-
ing not only the nervous system but the entire body,
with the muscles which move it; these, as is well seen
in the crab or lobster (which are the largest animals of
this group), being attached to the interior of the firm
casing. This skeleton is formed of a number of pieces
The centipede is a very character-
or segments, jointed or articulated together-whence the
The legs, as well as
name of the group.
istic illustration of this structure.
the body, are here seen to be enclosed in a firm envelope,
of which the pieces are connected together by a flexible
membrane; and the segments of the body are nearly
alike along its entire length. But in the higher classes
of this sub-kingdom, where the movement is perforined
entirely by the legs, as in Crustacea, or by the legs and
wings, as in Insects, the segments of the body to which
these are attached are firmly united together, in order to
give their muscles a fixed point from which to act. But,
in the lower classes, such as the leech and worm,
the extreme flexibility of the body, and the change of its
dimensions, are the only means of locomotion (no mem-
bers being present), the whole envelope of the body is so
soft, that the division into segments is scarcely percepti-
ble. The nervous system of the Articulata is not by
any means so highly developed as that of the Vertebrata;
in general, the organs of taste and vision are all that can
be detected in them; those of hearing and smell being
possessed only by a few of the higher tribes. The num-
ber of legs, when these are present, is often very great;
The blood
they are never less than six. More than one pair of
jaws usually exist, and they open laterally.
is white, and only in the highest classes is propelled by a
powerful heart. The Articulata have their whole struc-
ture adapted to great activity of locomotion, and to the
performance of instinctive actions of a high character.
The class in which this is most evident-that of Insects

where

The body, which is usually of small size, derives ite principal bulk from the organs of animal life, especially the muscles which move the extremities; and the lateral symmetry is even more remarkable in them than in the Vertebrata, extending in part to the organs of nutrition as well as to those of sense and motion.

The VERTEBRATA derive their name from the peculiarity of their skeleton, which essentially consists of a back-hone or spinal column, formed of a number of separate pieces, so united as to combine great strength with flexibility. These are termed vertebra. Each is perforated with a large aperture; and, when all are united, a continuous tube is formed, in which is lodged the spinal marrow, a very important part of the nervous system (this is quite different from the marrow of other bones, which is an oily substance, subservient to their nutrition). At one extremity, the spinal column is extended into a large bony structure, the skull, which is especially designed for the protection of the bruin (a large nervous mass, which may be regarded as an expansion of the spinal marrow) and of the organs of sense connected with it. At the other extremity it is contracted into a tail, the size and prolongation of which are usually greater in proportion to the small size of the skull.is by far the largest in the whole animal kingdom. Connected with this spinal column are a series of ribs, which pass off from it on each side, and generally meet again in a breast-bone, enclosing a cavity (that of the chest), in which are contained some of the organs of nutrition. Appended to it are two pairs of members or extremities, which are usually the instruments of locomotion. Although these are very differently formed in the different classes, they are essentially the same in all. The arms and legs of man, the four legs of a quadruped, the wings and legs of a bird, and the fins of a fish, are all exactly alike in their position, and in the elements of which they are composed. The skeleton of the Vertebrata is internal, being clothed with the muscles by which its various parts are moved; and, from what has been said, it is evident that it is particularly destined for the protection of the nervous system, which, from the high place of this group in the scale of animal beings, is the organ of the greatest importance in the whole structure. Vertebrated animals are endowed with all the special senses-sight, smell, hearing, and taste-the organs of which are situated in the head; besides the general sense of touch, which is common to the whole body. They have all red blood, which is propelled through the system by a muscular heart. The mouth is furnished

The group of MOLLUSCA must be described more by its negative than its positive characters. The body, as the name imports, is here soft, and destitute of any distinct skeleton. It is enveloped in a loose elastic skin, which is termed the mantle; and the outer surface of this has often the power of secreting a shell. But this shell is by no means adapted to the form of the animal; it has no regular series of joints for the purpose of facilitating the movement of the body, and it has no prolongations for giving protection and support to locomotive appendages. Moreover, of two species closely allied in general structure, it is often present in one and absent in the other, as in the snail and slug; and, when present in both, often differs much in form; so that it cannot be regarded as a part of the structure essential to our idea of a molluscous animal. That idea is principally founded upon the softness of the body, the high development of the organs of digestion, nutrition, &c.-in fact, of the

2 I

system of vegetative life, which constitutes the bulk of the body; and, on the contrary, the low development of the powers of sensation and locomotion, and the organs of animal life. Many of them are entirely fixed to one spot during all bu* the very earliest period of life; and in the lowest species there is a tendency to aggregation into a compound structure, like that which is seen in the zoophytes. The number of Mollusca possessing drive powers of locomotion is comparatively small; and of those which are not entirely fixed, the general character is sluggishness. The blood is generally white; and is often propelled by a powerful heart, and distributed through a complex system of vessels, even where the animal seems almost inert. Where any correspondence between the two sides of the body exists, it is usually restricted to those parts which are concerned in the functions of animal life; especially the head, on which the organs of special sense (when they exist) are placed.

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calls by the name of FISHES; and he naturally associates with it some of a higher class, which resemble it in ex ternal appearance and mode of life. Another large group he observes to be formed to pass a great part of its life buoyed up only by the air; that the form of its body, the construction of its members, and the peculiar covering with which these are invested, specially adapt it for this peculiar mode of support, and for rapid motion through the element it inhabits; and that it is incapable of existing for more than a few minutes under water. This is the class of BIRDS; and with it, also, the ordinary observer associates a portion of a superior class, which is adapted in part to a similar mode of existence. A third group would consist of animals possessed of four legs, adapting them to a residence on the earth, and to motion on its surface; these would also be found to agree in their incapability of living beneath water like fishes, or of rising into the air like birds. But further examination of these quadrupeds would disclose some important differences in structure and vital actions, which separate them into two great divisions, very widely apart from each other. It is soon observed that some are warm-blooded, maintaining a constant and elevated tem perature, while the others are cold-blooded, their bodily heat varying with that of the atmosphere, and in general being but little above it; that the former are covered with hair or something analogous to it, while the latter are coated with scales; and that the former produce their young alive, or are viviparous, and nourish them afterward by suckling, while the latter rear them from

The division RADIATA includes the lowest members of the animal kingdom, and those, therefore, which most nearly approximate to vegetables. There is a great tendency in the animals of this group to associate into compound structures, in which each individual has a certain degree of connection with the rest. Thus are formed those assemblages which, from their general resemblance to plants, are commonly called Zoophytes (animal-plants). Rut as, in investigating the characters of a tree, we study the separate flowers and leaves, so, in studying the zoophytes, we consider the individual polypes which form them. These polypes, in common with the higher kinds, of radiated animals, which are formed to exist separately; eggs, or are ovip trous. Hence this group is subdivided (such as the star-fish), are distinguished by the circular arrangement of their organs around a centre, in which their mouth is placed; and from this arrangement the name of the group is derived. There is thus a repetition of similar parts; and, as in most other instances where this is the case, a great power of reproducing those which have been lost. In many of the Radiata there is no distinct skeleton; in others a very firm support exists, almost always partaking of the circular arrangement of the soft parts. The sea-anemone is a good example of the lower forms of this group; the star-fish, or sea-urchin, of the higher very few species belonging to it possess much sensibility or power of locomotion. In many instances there are no distinct blood-vessels, but the nourishment is conveyed to the tissues by direct absorption from the external surface and from the walls of the stomach.

SUB-KINGDOM-VERTEBRATA.

Setting off with the idea of a vertebrated animal as one possessing an internal bony skeleton, essentially composed of a jointed spinal column, containing the spinal marrow, and expanded at one extremity into a bony case for the reception of the brain, having usually members or appendages for locomotion, which never exceed four in number, endowed with all the five senses, and in general with considerable activity, having red blood, and altogether a more complex organization than the lower classes possess, as well as a higher degree of intelligence-we next proceed to consider upon what principles this extensive group may be subdivided into others, which, agreeing in all these particulars, shall yet differ in other important characteristics.

The ordinary observer would readily establish three subdivisions or classes, upon the three well-marked types of form which he perceives to be adapted to existence in the three different elements. He sees that one large group is entirely confined to the water; that the form of its body is peculiarly adapted for motion in that medium; that its members are constructed for most advantageous propulsion in it; and that it is incapable of existing, at least for any length of time, out of it. This group he

by the naturalist into two, of which one-that of MaxMALIA-is superior in its general organization to birds, while the other-that of REPTILES-is intermediate between birds and fishes. The scientific characters of these groups will next be considered.

FISHES are oviparous vertebrata, inhabiting the water, and respiring that element by means of branchiæ or gills, which are filamentous prolongations of the surface, into which the blood is propelled, in order to be brought into relation with the air contained in the surrounding water. The heart only contains two cavities; one of these receives the blood which returns from the system, and the other propels it through the gills, from which it is conveyed by the blood-vessels to the body at large. They are in general cold-blooded, but few of them maintaining a temperature above that of the surrounding medium Living habitually in an element which is nearly of the same specific gravity with their bodies, fishes have no weight to support, and have only to propel themselves through the water. Accordingly we find their structure adapted for great freedom of motion, rather than for firmness and solidity; progressive motion is chiefly accomplished by the lateral action of the spine, which is endowed with great flexibility. The vertebræ, instead of being articulated by a flat surface, as in the Mammalia, or by a ball-and-socket joint, as in serpents, have each of their surfaces concave, and these glide over a bag of fluid, which is interposed between each pair of vertebrae. The tail is flattened vertically; and it is by its movement from side to side that the fish is urged forward as a boat by a sculler. The pectoral fins, which answer to the hands of man, and the ventral fins, which represent the feet, serve rather as steering than as propelling organs; and they also assist in raising and depressing the animal in the water. In a large proportion of this class, the skeleton is cartilaginous only; and in a few of the lowest the vertebral column is not divided into distinct portions, but forms one continuous tube of gristle, or even of membrane only. The surface of the body of fishes is almost always covered with scales; and these are sometimes quite bony, and fitted closely together, especially where the internal skeleton is soft.

REPTILES are also oviparous, cold-blooded vertebrata

combined to produce a more perfect degree of intelligence; the one most fertile in resources, most susceptible of perfection, and least the slave of instinct. Although principally adapted to motion on the ground, we find one tribe possessed of the power of rising into the air like birds, and another formed to inhabit the water like fishes; but both these agree with other Mammalia in all essential characters, and differ very widely from the classes with which their habits seem to associate them. To the Mammalia is confined the protection of the body by hair or fur; the nearest approach to it being in the hair-like feathers of a few species of birds. But the presence of this covering is by no means universal in the Mammalia.

CLASS I-MAMMALIA.

but in their adult state they breathe air, which is introduced of motion; and in which all the different faculties seem into lungs or internal cavities; and they mostly are formed to live on land-those which inhabit the water being obliged to breathe at the surface. Their heart possesses three cavities, one of which receives the blood from the lungs, and another from the system at large; the pure and impure blood are mixed in the third cavity, and the fluid is propelled by it partly to the lungs and partly to the body. Thus only part of the blood expelled from the heart is exposed to the influence of the air at each contraction; and this deficiency is accompanied by a general inertness of the other functions. Their motions are chiefly confined to crawling and swimming; for though a few at times can run and leap very quickly their general habits are siuggish, their sensations obtuse, and their digestion slow. Hence they can exist for a long time with a very feeble exercise of these functions, under circumstances that would be fatal to animals in which they are performed with greater activity. In cold and temperate climates they pass the whole winter in state of torpidity. There is greater diversity of form and structure among the members of this class, than in any other division of the vertebrated series. The tortoises, lizards and serpents appear so different, that a common observer would separate them widely; and yet they not only agree in all the foregoing characters, but pass into each other by links of transition so gradual that it is difficult to classify them. There is one group which, in its adult condition, bears a general correspondence with reptiles, and has been commonly associated with them; but which only arrives at this condition by passing through a kind of metamorphosis, like that of insects: this is the frog tribe, which includes several animals bearing the form of lizards and serpents, but differing from them in having a soft naked skin, instead of a scaly one, and in passing the early part of their lives-that which, in the frog, is called the tadpole state-in a condition like that of fishes in all essential particulars. These differences have been regarded by some naturalists as establishing their title to rank as a distinct class, to which the term AMPHIBIA has been given.

BIRDS are, like fishes and reptiles, oviparous vertebrata, and, like the true reptiles, they breathe air during the whole of their existence; but they are warm-blooded, having a heart with four cavities and a complete double circulation, by which all the blood returned from the system is transmitted to the lungs, before being distributed to it again. This high amount of oxygenation of the blood is accompanied by great activity and energy of all the organic functions, acuteness of the senses, and rapid and powerful locomotion. The class is further distinguished by the position of the body upon two legs only, and by the modification of the anterior members for wings; by the covering of the body with feathers, or something analogous to them; by the deficiency of teeth, in place of which the jaws are furnished with a horny covering or bill; and by various other characters of less importance. There is a peculiar conformity in the general structure and aspect of all the members of this class, with which scarcely any other animals are liable to be confounded. Birds have been not inappropriately termed the insects of the vertebrated classes.

The MAMMALIA agree with birds in possessing a complete double circulation and warm blood; and with reptiles in breathing air, and generally living on the surface of the earth; but they differ from all other vertebrata, not so much in producing their young alive (which is the case in a few species of reptiles and fishes), as in their subsequent nourishment of them by suckling from which circumstance the name is derived. This class is placed at the head of the animal kingdom, not only as being the one to which man belongs, but also because it is that which enjoys the most numerous faculties, the most delicate sensations, the most varied powers

The Mammalia are universally regarded as constituting the highest group in the animal kingdom; not only from being the one to which man belongs (so far, at least, as his bodily structure is concerned), but also as possessing the most complex organization, adapted to perform the greatest number and variety of actions, and to execute these with the greatest intelligence. The contrast is here extremely strong between the reasoning and the instinctive powers. When we compare the sagacity of a dog, and the great variety of circumstances in which he will display an intelligent adaptation of means to ends, with the limited operations of the insect, over which the judgment and will seem to have no control, we cannot help being struck with the difference. The one is educable in the highest degree next to man; the other could not be made to change its habits by the most prolonged course of discipline. In ascending the animal scale, we observe the instincts gradually becoming subordinated to the reasoning powers; and this may be particularly noticed among the members of the class under consideration, which exhibit much variety in this respect. If we regard intelligence as the chief characteristic of the Mammalia, we should perhaps rest upon the principal varieties in the degree in which this is possessed by the several subordinate groups, as the groundwork of our division of the class into orders. But for the sake of convenience the naturalist seeks for other characters, and more particularly aims to establish his classification upon such as are external and easily recognised. Such a classification will be natural, that is, will most nearly associate together the animals that have the greatest general resemblance, and will most widely separate those which have the least, in proportion as the characters which are selected for the purpose may be regarded as indicating the general conformation of the several animals. In this respect, the structure of the extremities, and the arrangement of the teeth, are found to be the most valuable.

From the general structure of the extremities, we may learn much of the habits of the animal, and the adaptation of its whole organization to a particular mode of life. These, for example, would be at once determined by an inspection of the wing of a bat or the flapper of a whale. Hence we shall not be far wrong if we throw into distinct groups all the Mammalia possessing one or other of these modes of conformation. But among those which are adapted to walk upon land, we must seek for some slighter differences; and such we may in the first place look for in the organs of touch, since on these will depend much of the address of the animal, and a number of differences connected with the amount of its intelligence. The degree of perfection of the organs of touch is estimated by the number and mobility of the fingers, and the greater or less extent to which their extremities are enveloped by the nail or hoof. When the fingers are partly absent or consolidated together, and a hoof envelops all that portion which touches the ground, it is

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