M A M MALI A. 



177 



though his means of defence against attack are ex- 

 ceedingly powerful, he wages no offensive war except 

 against the vegetable kingdom. Even there, though 

 he is not a welcome guest in cultivated countries 

 where crops are grown close to the banks of those 

 rivers from which he never wanders very far ; yet in 

 that wild and exuberant state of nature, which alone is 

 compatible with the existence of the elephant, the 

 rhinoceros, and those powerful animals of the order 

 which are now gone, he is as completely in his place, 

 and as useful in the system of nature, as the most 

 graceful animal which roarns the plains or browses 

 the meadows. The tusks of the hog are another of 

 the exceptions ; and though when attacked this ani- 

 mal can inflict desperate wounds by means of them, 

 their object in the natural economy of the animal is 

 not that of wounding, but of tearing other substances 

 than the flesh of living animals. 



We cannot, however, come to any specific conclu- 

 sion respecting the teeth of this order of mammalia ; 

 for whether the series was or was not complete at 

 some former period, it is now so broken, and there is 

 so little correspondence between one genus and 

 another in this respect, that we cannot make a tran- 

 sition ; and this is the reason why Cuvier, notwith- 

 standing his profound knowledge of animal structure, 

 and the agreement of the parts and the system 

 with each other, was obliged to found the character 

 of these animals upon the thickness of the skin, which 

 is wholly of an external kind, and furnishes no guide 

 whatever to any part of their economy, either as to 

 what food they eat or how they procure it. 



Respecting the digestive system of the mammalia, 

 there are but few general remarks which can be 

 made apart from those which are the foundations of 

 {the classification. It is obvious that the organs of 

 digestion must be adapted to the nature of the food ; 

 and that therefore they must in a great measure 

 correspond with the teeth, which are adapted to the 

 same purpose. 



The general principle is that the coarser the ordi- 

 nary food of the animal is, its organs of digestion are 

 ;!K> more enlarged and complicated. This however 

 onus a sort of guide, though rather a loose one, to 

 ome points in the progressive history of the mam- 

 nalia. The larger pachydermata are, for instance, 

 dapted to a state of things in which vegetation is 

 ank and coarse ; and this again points to a humid 

 ondition of the surface of the earth, at least in the 

 daces inhabited by those animals. But the remains 

 >f such animals have been met with in almost every 

 egion of the world where men have had an oppor- 

 unity of exploring the soil ; and this leads us to the 

 :onclusion, that at some former period of its history, 

 he earth must have abounded much more generally 

 vith water, both stagnant and running, upon the 

 urface of the land than it does now. 



We might even go further than this, were it not 

 hat it would involve us in a more extended history 

 han that of the mammalia, and not only so, but lead 

 is to the consideration of departed races of verte- 

 )rated animals, both swimmers and fliers, and some 

 >erhaps capable of performing both these motions, to 

 vhich there is no likeness, or near approximation to 

 likeness, in any known animal which is now found 

 ilive. The farther investigation of this point, 

 urious though it be, thus belongs to the general 

 u'story of animated nature iu its progress, or more 

 trictly speaking to the progressive history of the 

 NAT. HIST. VOL. III. 



globe itself, than to the history of any particular 

 class of existing animals. 



Next to the pachydermata, the animals which 

 have the organs of digestion the most elaborate and 

 enlarged are the ruminants, of which we shall have 

 to say a few words afterwards ; and as they have a 

 double labour to perform both with the mouth and 

 the stomach, part of the enlargement is of necessity 

 taken up by this doubling. The ruminants belo.ng 

 to a different state of things from the pachyderma^ 

 tous animals ; although, as both are vegetable feeders, 

 they have a slight approximation to each other on 

 the confines. The ruminants belong to an era of 

 more humble, but more kindly vegetation than the 

 pachydermata ; and therefore they appear to have 

 come later in those places of the earth where both 

 have inhabited. Not only this, but the species or 

 varieties which are found only in the earth, are larger 

 than the existing ones of the same places. It is true 

 that in several instances the domesticated varieties 

 are often larger than what we may consider as being 

 the extinct natives. We can, however, draw no safe 

 conclusion from this with regard to the natural pro- 

 gress ; for where man cultivates, he always brings a 

 more rich and succulent vegetation over the soil, 

 than that soil would yield without the benefit of his 

 labour, unless in places where the natural tendency 

 is to be overrun by forest trees, or by brushwood. 



In proportion as the food of the vegetable feeder 

 begins to partake more of the pulpy or farinaceous 

 character, the organs of digestion become smaller 

 and simpler. In the miscellaneous feeders they are still 

 more so, and the decrease becomes more and more, 

 according as the food becomes more and more animal. 



It is not very easy to say what particular states of 

 countries are best adapted for those animals whose 

 food differs but by small shades, and which can in 

 consequence turn readily to one when another fails. 



When we come to the carnivorous animals, we 

 must attend to the nature of their food, and the 

 means they have of catching it ; and as the more 

 powerful ones prey chiefly upon vegetable feeders, 

 we are sent back again to inquire what condition of 

 the earth's surface is best adapted for furnishing an 

 abundant supply of these. Thus when we attempt 

 to turn the mammalia into an index to the progres- 

 sive natural 'geography of the earth, we find that 

 there are some doublings which carry us back very 

 nearly to the point at which we set out, and by this 

 means involve us in difficulties from which we are 

 unable to escape. 



The remarks which we have made in this section, 

 and in which we have endeavoured to select the most 

 characteristic animals, and speak of the leading func- 

 tions of their organs, must suffice for this highly in- 

 teresting branch of the study of the mammalia, which 

 is, in a great measure the key to the philosophy of 

 the whole. 



SEC. VI. CLASSIFICATION OF THE MAMMALIA. 

 There is no branch of natural history which has 

 received more improvement at the hands of the lead- 

 ing naturalists of modern time?, than classification ; 

 and though this may seem to be but a humble branch 

 of the subject, it is not so in reality, at least when 

 founded on views sufficiently extensive, and pursued 

 in the spirit of candour and discernment. In theoreti- 

 cal proof of this we need only remark, that the best 

 classifications of animals, to which part soever of the 

 kingdom they belong, have always been projected 

 M 



