general plan that terms must occasionally be employed which have not been previously defined, and of which, in a regular treatise, the expianation would necessarily precede the use. To obviate this inconvenience as much as possible, it is proposed, without entering into the minute details of the subject, or anticipating information which properly belongs to a different part of the work, to give a brief explanation of such terms as they occur; so that the general reader may be enabled to comprehend their meaning and import without the trouble of referring to other sources.

Before commencing the history and description of the genus which more properly constitutes the subject of the present article, we shall, therefore, give a short explanation of the terms Mammalia and Edentata, as well as of the technical import of the words Class, Order, Genus, and Species, which are of constant occurrence in Zoology: these terms would otherwise be obscure or unintelligible to an ordinary reader.

The word Mammal (Mammalia is the Latin form of the plural) was formed by Linnæus from the Latin mamma, signifying a breast or udder, in the same manner as our common word animal is formed from anima, life or soul; and was intended to denote those animals which suckle their young, and for which there is no generic name in any known language sufficiently definite and comprehensive. The common word Quadruped, which more nearly expresses the exact idea than any other, has no relation to the natural affinities which we observe among animals, since it excludes inan and the cetaceous tribes (such as whales), at the same time that it comprehends the lizards, tortoises, and other reptiles, which have but a very remote analogy to the true Mammalia.

The vernacular term Beast, which we often use in opposition to Birds and Fishes, is still more vague and indeterminate. The word Mammal, however, so happily imagined by the great Swedish naturalist, is liable to none of these objections, but expresses, in a distinct and definite manner, the most prominent functions and natural limits of this class of animals. In the constant use which we shall be obliged to make of this term, we shall adopt the common English form of the plural, Mammals, instead of the Latin form, Mammalia, though the latter is most generally used by British zoologists. The word Mammals is as regularly formed, and therefore as admissible into the English language, as animal and animals.

Mammals, therefore, in the technical language of zoologists, constitute a class, or primary division of the animal kingdom; and are, in this respect, co-ordinate with Birds, Fishes, Reptiles, and Insects; all of which are so many Classes. The term Order denotes a subordinate division, and bears the same relation to a class which this latter does to a kingdom; so that a class is made up of orders, in the same manner as a kingdom is made up of classes. The next inferior sub-division to an order is a Genus; and this is itself composed of Species, the lowest link in the chain of scientific classification, and that which admits of no further division. A species, then, comprehends all those animals which may reasonably be supposed to be descended from one common, original stock; and in this sense all men compose but a single species, all horses compose but a single species; and in the same manner all oxen, sheep, goats, dogs, &c. compose respective and appropriate species. Difference of climate, variety of food, and other local and extraneous circumstances, undoubtedly produce striking changes in the form, size, and colour of different individuals, even of the same species; examples of which are sufficiently abundant among all domestic animals, and that, too, in exact proportion to the degree of their domestication, and to the care and attention which have been bestowed upon them by man. But these variations are confined within certain prescribed limits, and the utmost power and ingenuity of man have been exerted in vain to produce and perpetuate a new race or species of animals. He has succeeded, to be sure, in procuring the Mule from the intercourse of the Horse and the Ass, two very distinct species, though in some respects closely allied to one another; but this mule is itself a barren, unproductive being, which Nature regards as a monster, and to which she has denied the power of continuing its

race.

An example will best illustrate the true import of the terms which we have been here endeavouring to explain. Thus the dog, the fox, the wolf, and the jackal, are all so many species of one common genus; as are likewise the

lion, the tiger, the panther, the lynx, and the common cat, species of another genus. These are respectively called the genus Canis, or the dog kind, and the genus Felis, or the cat kind; and compose, together with the hyænas, oivets, weasels, bears, badgers, &c. the natural Order of Carnivora, or flesh eaters, which have six incisor or front teeth in each jaw, and live upon the flesh of other animals. Another natural order of Mammals comprises all those which, like the rat, the squirrel, the rabbit, and the guinea-pig, have only two large teeth in front, which they continually employ in gnawing whatever falls in their way; they are, therefore, called Rodentia, or gnawers. These, at least in the number of their incisor teeth, form the intermediate link which connects the Carnivora with the Edentata, or next order of Mammals, which are distinguished by having no front teeth at all, and are therefore constrained to live entirely upon a vegetable regimen, or upon insects, carrion, and other soft substances which require little cutting or mastication. These different Orders of Carnivora, Rodentia, and Edentata, together with the Ruminantia or ruminating animals, the Cetacea or whale kind, and others less important, which it is unnecessary here to enumerate, compose the class Mammalia.

Having thus briefly explained the signification of those technical terms which will occur most frequently in the subsequent Zoological articles, we shall return from this digression to the more immediate object of our present consideration.

The Orycteropus is now separated from the Myrmecophaga, or Anteaters of Linnæus, with which it had been formerly associated. In its anatomical structure. it bears a much closer relation to the armadillos than to any other quadrupeds, not even excepting the ant-eaters, with which it was formerly associated. Like these animals, the orycteropus has neither incisors nor canine teeth; and its feet are equally provided with large and powerful claws, for digging up roots and insects, and for forming subterraneous burrows. Its molar teeth, however, are altogether peculiar both in form and structure, and have no resemblance to the teeth of any other known animal. Of these there are five large ones on each side (both in the upper and under jaws), which are always permanent; and a variable number of from one to three smaller ones, placed in front of the others, and apparently representing the false molars of ordinary quadrupeds. The first of the large molars is smaller than any of the other four, and of a cylindrical form, somewhat compressed or flattened on the sides; the second is rounder; the third and d

B

Teeth of the Aard-vark (Orycteropus Capensis).

A Two views of the upper jaws, showing, a the surface of the teeth, b the sides

B, c. d, Ditto of the lower jaw.

C The teeth in their natural position.

fourth are each composed of two similar cylinders, as it were, soldered together, and the last is a simple cylinder, like the first and second. Immediately in front of these are the small or false molars, which, being of a deciduous nature (falling annually), vary in number according to the individual. In their internal structure these teeth differ from those of all other animals. They are pierced throughout their whole length with an infinite number of small capillary tubes, running in the same longitudinal direction, and opening at the root or under part of the teeth. The crowns or upper surfaces of the teeth are covered with enamel, but after this has been worn away by the continued process of mastication, as in very old animals, the openings of these small canals may be plainly distinguished upon the surface also; and in this state, the teeth, to use the appropriate comparison of Baron Cuvier, resemble the joint of a cane cut across, and exhibiting the numerous minute vessels which perforate its interior. Properly speaking, these teeth are destitute of real roots, and are therefore, like the tusks of the elephant, and the incisors of the rodentia, capable of being indefinitely increased, by the deposit of new matter on the under extremity, to counterbalance the continual wear of the upper surface.

In the form of the extremities the orycteropus resembles the armadillos still more nearly than in the nature of its dental system. The legs are remarkably short and stout; the feet plantigrade (that is to say, the animal walks upon the whole sole of the foot, as man and the bear, instead of bringing the point of the toe only in contact with the ground, as may be observed in the dog, horse, &c.); and the toes, of which there are four on the fore feet and five on the hind, are armed with extremely large, powerful claws, flattened horizontally, and scooped or hollowed out on the under surface, so as to form a most efficient instrument for digging and burrowing beneath the surface of the earth. This process is still further facilitated by the oblique form of the anterior extremities, arising from the unequal length of the toes; the two interior being considerably longer than the others, and the whole diminishing gradually from the index (or toe corresponding with the fore-finger) outwards. In other parts of its anatomy the orycteropus resembles both the armadillos and the ant-eaters, and particularly in the form and structure of the stomach and alimentary canal. The reader who is desirous of further information upon these subjects may consult Cuvier's Leçons d'Anatomie Comparée, and his great work Sur les Ossemens Fossiles, from which the details here given are for the most part abridged.

The only species of this curious genus with which zoologists are at present acquainted is the Aard-Vark (Orycteropus Capensis), called innagu by the Korah Caffres, and goup by the Hottentots. It is an animal extremely common in some parts of Southern Africa, though, from its nocturnal habits and extreme timidity, it is not so frequently seen as many others which are in reality scarcer. Its colonial name of aard-vark, or earth-pig, by which it is known among the Dutch inhabitants of the Cape of Good Hope, is derived as well from its habit of burrowing as from the general appearance which it bears, at first sight, to a small, short-legged pig. This animal, when full grown, measures about three feet five inches from the snout to the crigin of the tail; the head is eleven inches long; the ears

I six inches; and the tail one foot nine inches. The head is long and attenuated; the upper jaw projects beyond the lower, and ends, as in the common hog, in a truncated, callous snout, having the nostrils pierced in the end of it; the mouth is small for the size of the animal, and the tongue flat and slender, not cylindrical as in the true ant-eaters, nor capable of being protruded to such an extent as in these animals: it is, however, covered in like manner with a viscous or glutinous saliva, which firmly retains the ants upon which the animal lives, and prevents those which once come into contact with it from escaping afterwards. The ears are large, erect, and pointed; and the eyes, which are of moderate size, are situated between them and the snout, about two-thirds of the distance from the extremity of the latter. The body of the aard-vark is thick and corpulent; the limbs short and remarkably strong; the hide thick, tough, and nearly naked, having only a few stiff hairs, of a pale reddish-brown colour, thinly scattered over it, excepting on the hips and thighs, where they are more numerous than elsewhere. The tail is about half the length of the body and head together, and, like the body, is nearly naked; it is extremely thick and cylindrical at the base, but decreases gradually towards the extremity, and ends in a sharp point.

Thus formed, the aard-vark is in all respects admirably fitted for the station which Nature has assigned to it in the grand economy of the animal kingdom. It feeds entirely upon ants, and in this respect fulfils the same purpose in Southern Africa which is executed by the pangolins in Asia, the myrmecophaga in America, and the echidna in New Holland. To those who are only acquainted with the size and nature of these insects in the cold northern climates of Europe and America, it may seem surprising how an animal so large as the aard-vark can support itself exclusively upon ants, and yet be invariably found fat and in good condition. But the ants and termites of tropical countries are infinitely more numerous than those which inhabit more northern latitudes, and so large as sometimes to measure an inch or an inch and a half in length. The bodies of these ants are, besides, of a soft, unctuous nature; and travellers inform us that the Hottentots themselves frequently collect them for food, and even prefer them to most other descriptions of meat. Patterson affirms that prejudice alone prevents the Europeans from making a similar use of them; and says that, in his different journeys, he was often under the necessity of eating them, and found them far from disagreeable. However this may be, their importance in fattening poultry is well understood at the Cape, and the farmers collect them by bushels for this purpose.

These insects raise mounds of an elliptical figure to the height of three or four feet above the surface of the ground; and so numerous are these gigantic ant-hills in some parts of Southern Africa, that they are frequently seen extending over the plains as far as the eye can reach, and so close together that the traveller's waggon can with difficulty pass between them. They abound more especially in the Zeurevelden, or sour districts, so called from producing a kind of sour grass; are seldom found on the karroos or downs, and never in very dry or woody districts. By constant exposure to the rays of a powerful tropical sun they become so hard and indurated on the outer surface that they easily support the weight of three or four men, and even a loaded waggon will sometimes pass over without crushing them. Internally these mounds are of a spongy structure, something resembling a honeycomb, and are so completely saturated with animal oil that they inflame without difficulty, and are an excellent substitute for wood or coal.

Wherever ant-hills abound the aard-vark is sure to be found at no great distance. He constructs a deep burrow in the immediate vicinity of his food, and changes his residence only after he has exhausted his resources. The facility with which he burrows beneath the surface of the earth is said to be almost inconceivable. We have already seen how admirably his feet and claws are adapted to this purpose; and travellers inform us that it is quite impracticable to dig him out, as he can in a few minutes bury himself at a depth far beyond the reach of his pursuers; and, further, that his strength is so great as to require the united efforts of two or three men to drag him from his hole. When fairly caught, however, he is by no means retentive of life, but is easily dispatched by a slight blow over the snout. The aardvark is an extremely timid, harmless animal, seldom removes to any great distance from his burrow, being slow of foot and a bad runner, and is never by any chance

found abroad during the day-time. On the approach of night he sallies forth in search of food, and, repairing to the nearest inhabited ant-hill, scratches a hole in the side of it just sufficient to admit his long snout. Here, after having previously ascertained that there is no danger of interruption, he lies down, and, inserting his long slender tongue into the breach, entraps the ants, which, like those of our own country, fly to defend their dwellings upon the first alarm, and, mounting upon the tongue of the aardvark, get entangled in the glutinous saliva, and are swallowed by whole scores at a time. If uninterrupted, he continues this process till he has satisfied his appetite; but on the slightest alarm he makes a precipitate retreat, and seeks security at the bottom of his subterranean dwelling. Hence it is that these animals are seldom seen even in those parts of the country in which they are most numerous. Like other nocturnal animals, which pass the greater part of their lives in sleeping and eating, they become exceedingly fat, and their flesh is considered to be a wholesome and palatable food. The hind-quarters, particularly when cut into hams and dried, are held in great esteem, and are much sought after by colonial epicures.

AARD-WOLF (Proteles, Is. Geof.), in Zoology, a genus of digitigrade carnivorous mammals founded by M. Isidore Geoffroy St. Hilaire for the purpose of giving a place to a new and singular quadruped brought from the interior of Caffraria by the late traveller Delalande. The three specimens of this interesting animal procured by M. Delalande were all, unfortunately, of an immature age, and had not acquired their permanent teeth, so that the characters of their adult dentition still remain to be determined. Enough, however, is known to enable us to assign the most prominent and influential characters of the genus, and to infer, with a tolerable degree of accuracy, the habits and economy of the animal.

It is an observation at least as old as Pliny, that Africa is a land of wonders, which continually produces a succession of new and singular objects. In zoology, the maxim of the Roman philosopher, as to African wonders, is verified almost daily. Among the most recent examples of this fact we may adduce the discovery of the proteles; an acquisition of peculiar interest to the zoologist, as forming the intermediate link which connects the civets with the dogs and hyænas, three genera which have hitherto stood, as it were, insulated from surrounding groups, and widely separated from one another. The dogs and hyaenas, indeed, had been united a short time previous by the discovery of an intermediate species in the same locality which has since produced the proteles; but it is this latter species alone, which, uniting the characters of all these three genera, enables us to trace their natural affinities, and to assign to them their proper position in the scale of existence.

To the external appearance and osteological (bony) structure of a hyæna, this truly singular animal unites the head and feet of a fox, and the teeth and intestines of a civet. It has five toes on the fore feet, and four only on the hind; the innermost toe of the fore foot is placed, as in the dogs, at some distance above the others, and therefore never touch the ground when the animal stands or walks. The legs also are completely digitigrade; that is to say, the heel is elevated, and does not come into contact with the surface, as in man and other similarly formed animals which walk upon the whole sole of the foot, and are thence said to be plantigrade. It is of great importance to remark the difference between these two modifications of the locomotive organs, because they have a very decided and extraordinary influence upon the habits and economy of animal life. Digitigrade animals, which tread only upon the toes and carry the heel considerably elevated above the ground, have much longer legs than plantigrade animals, and are therefore especially fitted for leaping and running with great ease and rapidity. Accordingly, it will be observed that the horse, the stag, the antelope, the dog, and other animals remarkable for rapidity of course, partake strongly of this formation; and even their degree of swiftness is accurately measured by the comparative elevation of the heel. Inattentive observers sometimes misapprehend the nature of this peculiar conformation of the extremities of digitigrade animals, and are apt to confound the hough with the ankle, and to mistake for the knee what is really the heel of the animal. Thus we have heard it said that, in the hind legs of the horse, the knee was bent in a contrary direction to that of man. This is by no means true: a little attention to the succession of the different joints and articulations will show that what is called the cannon-bone in the

horse, and other digitigrade animals, in reality corresponds to the instep in man, and that what is generally mistaken for the knee really represents the heel.

In the particular case of the proteles the natural effect of the digitigrade formation is, in some degree, lessened by the peculiar structure of the fore legs, which, contrary to the general rule observable in most other animals, are considerably longer than the hind. In this respect, also, the proteles resembles the hyænas; and in both genera this singular disproportion between the anterior and posterior extremities abridges the velocity properly due to their digitigrade confor mation. It has been already observed that the only individuals of this genus which have been hitherto properly observed were young specimens, which had not acquired their adult dentition; but it was sufficiently obvious to the experienced eye of M. Cuvier, who first examined them, that the dental system of the mature animal must very closely resemble, if it be not actually identical with, that of the civets and genets. The young animal presented three small false molars and one tuberculous tooth on each side both of the upper and under jaws; and we shall find, in the sequel, that the approximation of M. Cuvier is fully justified by the evidence of another accurate observer, who had an opportunity of examining this animal in its native regions. The genus proteles contains but a single species,

the Aard-wolf, or earth-wolf (Proteles cristata), so called by the European colonists in the neighbourhood of Algoa Bay, in South Africa, the locality in which M. Delalande procured his specimens of this animal. The size of the aard-wolf is about that of a full-grown fox, which it further resembles in its pointed muzzle; but it stands higher upon its legs, its ears are considerably larger and more naked, and its tail shorter and not so bushy. At first sight it might be easily mistaken for a young striped hyæna, so closely does it resemble that animal in the colours and peculiar markings of its fur, and in the mane of long stiff hair which runs along the neck and back: indeed, it is only to be distinguished by its more pointed head, and by the additional fifth toe of the fore feet. The fur is of a woolly texture on the sides and belly, but a mane of coarse, stiff hair, six or seven inches in length, passes along the nape of the neck and back, from the occiput to the origin of the tail, and is capable of being erected or bristled up, like that of the hyæna, when the animal is irritated or provoked. The general colour of the fur is pale cinereous (ash-coloured), with a slight shade of yellowish-brown: the muzzle is black and almost naked, or covered only with a few long stiff moustaches. Around the eyes, and on each side of the neck, are dark brown marks; eight or ten bands of the same colour pass over the body in a transverse direction, exactly as in the common striped hyæna; and the arms and thighs are likewise marked with similar transverse stripes. The legs and feet are an uniform dark brown in front, and grey behind. The long hairs of the mane are grey, with two broad rings of black, the second of which occupies the point; those of the tail are similarly marked, and equally long and stiff; whence it appears as if the mane and tail were clouded with an alternate mixture of black and grey. The ears are grey on the interior, and dark brown on the outer, surface.

In its habits and manners the aard-wolf resembles the fox: like that animal it is nocturnal, and constructs a subterraneous burrow, at the bottom of which it lies concealed during the day-time, and only ventures abroad on the approach of night to search for food and satisfy the other calls