398 ZOOLOGY. 



them. In the case of mammals living in pairs, as in Carnivora, the male 

 usually takes his part in tliis safeguard. 



All mammals have a voice, which is very diversified, although not so 

 much so as in birds. 



Among all classes of animals, that of mammals is undoubtedly the one 

 which is the most profitable to man, especially the domesticated kinds. 

 Their flesh serves as food, as also the milk. The skin, fur, hair, and wool 

 have a thousand applications. Several animal substances are used as 

 medicines, and others as perfumery, still others as fuel (as for instance, the 

 excrements of the camel) ; teeth, bones, hairs, horns, antlers, entrails, skin, 

 muscle, tendons, as also blood and fat, are worked up and made use of in 

 various ways. Finally, many serve us as guides in hunting, as beasts of 

 burden, or as vigilant guards of life and property. 



The class of mammalia exhibits the greatest variety of habits among its 

 members. Created to inhabit chiefly dry land, it is met with in every 

 situation and locality, from the edge of the water to the top of the moun- 

 tains, from the surface of the ground and under it to the top of the trees, in 

 forests, open land, dry and wet, everywhere, exposed to the bright sun of 

 the equator and to the frozen regions of the poles. Some frequent watery 

 places, the banks of rivers, lakes, the beaches and sea shores Still others, 

 entirely pelagic, are never seen near the land, except when thrown ashore 

 by storms or other accidental causes. Again, in relation with all these 

 circumstances of habitation, there are habits and instincts by which each 

 species secures its food, escapes the dangers of its enemies or attacks :.i 

 defenceless prey, and provides for the perpetuity of its race. 



Classification. 



Of the numerous systems of classification of mammals hitherto proposed, 

 no one appears satisfactory to us. From the time that whales and dolphins 

 {Cetacea) were acknowledged to be mammals, they have been considered 

 as the lowest of all, on account of their inhabiting the water, and the 

 analogy of their form with that of fishes. In all systems of classification 

 they are placed lowest. This position is assigned them in the Systema 

 Naturae of the great Linnaeus. In Cuvier's Animal Kingdom, the Cetacea, 

 as usual, are placed at the bottom of the class, the Ruminantia come next, 

 then P achy der mala, then Edentata, then Rodentia, then Marsupialia, then 

 Carnivora, Insectivora, Cheiroptera, and, finally, Quadrumana. Others 

 make Pachydermata follow the Cetacea and precede Ruminantia, which 

 appears to us much more correct. But the place assigned to Edentata and 

 Marsupialia, we believe, is arbitrary, for, as they stand, they rather obscure 

 than enlighten the affinities of the neighboring orders. 



During the last ten years, a modification has been introduced into our 



systems, which consists of dividing the class into two sub-classes, namely, 



the Monodelphes, including the generality of mammals whose young, when 



just born, require no other care from their parent except to suckle thenj ; 



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