MAMMALIA. 



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they serve, besides conveying the animals to the 

 places where their food is found. 



They may be regarded as forming three principal 

 divisions : tirst, feet which serve for walking, and for 

 hardly any other purpose ; secondly, feet which 

 serve for walking and also for preparing a den or 

 burrow in the earth, in which the animal shelters 

 itself, or finds a security for its young ; and thirdly, 

 feet which in addition to the function of walking, 

 serve the animal as prehensile instruments in imme- 

 diately seizing its prey. 



The foot which performs the single function of 

 walking, we need hardly say, performs that function 

 better than any of the rest do, upon the obvious 

 principle that an organ which has more than one func- 

 tion to perform, cannot work with its whole energy in 

 the performance of either of them ; and thus a certain 

 portion of the power of the animal lies idle while it 

 is performing either the one or the other. We ac- 

 cordingly find that those animals which use their 

 feet simply for walking, are larger, and also subsist 

 on coarser food, or food which requires to be taken 

 in larger quantities than that of animals with double 

 functioned feet. Those which use the feet in bur- 

 rowing are, generally speaking, small animals, but 

 strong in proportion to their size. This is obviously 

 necessary in consequence of the additional labour 

 which they are required to perform. A common mole, 

 for instance, is much stronger in proportion to its 

 size than an elephant ; and the labour which it has 

 to perform in making its way under ground is far 

 greater than that of almost any animal which lives 

 upon the surface without burrowing. In proportion, 

 however, as it is better adapted for making its way 

 through the earth, it is worse adapted for walking on 

 the surface. An outward motion is required in the 

 digging feet, and this is inconsistent with the best 

 form of articulation in the legs, and also in the feet 

 for a free forward motion in walking, with nothing 

 but its own weight to carry. The case is similar 

 with all other animals which are expert burrowers, 

 for they cannot obtain that faculty except at the 

 sacrifice of a certain portion of their power in 

 walking. 



With those animals which use the feet as pre- 

 hensile instruments, the case is somewhat similar, 

 and as these are wholly or nearly all carnivorous, it 

 becomes necessary that they should be capable of 

 exerting more power occasionally than they can con- 

 tinue to exert for any length of time. Their prey is 

 more substantial, however, than that of any other 

 mammalia, and thus they are able to enjoy longer 

 intervals of repose ; their lives being made up of 

 short and violent exertions, interspersed with much 

 indolence. The cat tribe, more especially lions, 

 tigers, and the other more powerful ones, afford good 

 illustrations of what has been now stated. 



Those predatory animals which course their prey, 

 or follow it on the scent, furnish a different spe- 

 cies of illustration. Generally speaking, they do 

 not require that violence of temporary exertion 

 which the others must practise, and therefore they 

 can make more continual exertions. Their most 

 violent exercise is that of running ; and though some 

 of them strike down their prey with the foot, and 

 others turn it by the motion of the head, yet none of 

 them can be said to clutch their prey by means of 

 their claws. They generally also have more or less 

 of a digging or burrowing habit when in a state of 



nature ; for though some of the domesticated breeds 

 of dogs have not much tendency to burrowing, we 

 can draw no conclusions from them with regard to 

 the habits of dogs in a state of nature. 



We might, from the mere consideration of their 

 structure and habits, be led to conclude that mam- 

 malia which have walking feet, should be by far the 

 most useful to man. Like him, their proper habita- 

 tion in all the principal parts of their economy is on 

 the surface of the ground. Like man too, their feet 

 are simply walking feet, and whatever other opera- 

 tions they have to perform, are performed by other 

 parts of their bodies. It is true that they walk upon 

 four feet, while man walks only on two ; but in the 

 grand operation of finding their subsistence, the mouth 

 is the only instrument with which they are furnished 

 in addition to their walking feet, and as this operation 

 in them is from the nature of their food and its abun- 

 dance, an exceedingly simple one, the mouth is quite 

 adequate to the performance of it ; and if the food 

 requires to be " gathered in," as is the case with that 

 of most animals which graze, a peculiar prehensile 

 power is given to the lip, so that that organ secures 

 what is divided by means of the jaws. This provision 

 is of great service to these animals, inasmuch as, in 

 the majority of this species, they must find their food 

 nearly on a level with the ground on which they 

 stand, and thus it has to be carried up to the throat 

 against the resistance of gravitation. 



Mammalia of this description do not require the 

 same resources as those which prey upon animals ; 

 but still as the breadth of surface which they have to 

 range is considerable, and as many of them have to 

 move from place to place with the seasons, they have 

 more animal sagacity than one would suppose. In- 

 deed, as they are the animals chiefly preyed on by 

 the more powerful carnivora, they require a consider- 

 able degree of watchfulness and resource, in order to 

 avoid their enemies. 



There is another circumstance which tends farther 

 to adapt those animals to the use of man, and that is, 

 the fact of their being all gregarious, or social in a 

 state of nature. This circumstance of sociality is in 

 a great measure the basis of domestication ; for ani- 

 mals which live solitary, or in single pairs in the wild 

 state, though they may be kept in confinement, can- 

 not be domesticated without the greatest difficulty. 

 Even in the same genus of animals, if we find a species 

 inhabiting by the single pair, while the other species 

 are social, it is an almost invariable proof that this 

 species will be far more difficult to bring into a state of 

 domestication than the others. Among the deer, for 

 instance, the roebuck is, of the species with which we 

 are well acquainted, the only one which lives in single 

 pairs apart from each other ; and the wildness of the 

 roebuck as compared with the fallow deer, or even 

 with the stag, is quite proverbial. 



The same leading ground of domestication occurs 

 in other animals, even in those which are predatory. 

 The dog family, including the hyaena, may be said to 

 be the only race of predatory animals which have 

 been domesticated for generally useful purposes ; for 

 the domesticated cats are kept avowedly in order 

 that they may pursue in houses the same habits which 

 the smaller ones of the genus pursue in wild nature ; 

 and though they have a knowledge of persons as well 

 as of places, at least to a certain extent, they do not 

 evince any thing which can be called attachment to 

 or affection for, even those who are most kind to 



