MAMMALS. 603 



present. This organ is however wanting in the Monotremes, the 

 Cetaceans, many seals, the mole, &c. In the true whales the 

 external auditory aperture is a capillary passage 1 . 



The motions of mammals consist principally in progressing ; 

 some are able to spring very well, others are formed for swimming. 

 In the true cetaceans, swimming is the sole motion: some mam- 

 mals are able to fly by the assistance of a membrane extended 

 between the much elongated fingers of the fore limbs (the bats) ; 

 others flutter, or avail themselves in springing of a parachute, 

 formed by a prolongation of the skin along the sides of the body 

 between the fore and hind limbs ( Galeopithecus, Pteromys, Petau- 

 rista) . 



The regenerative power in mammals is small. Their intellectual 

 power is more developed than that of any other animals; many 

 domestic animals are exceedingly docile, and thus are able to 

 perform important services for man. Hence the mammals stand 

 in close relation to the history of mankind; the exercise on the 

 part of man of his mastery over those animals which could be of 

 service to him, was one of the first efforts he was obliged to make 

 in order to lay a foundation for the further development of civiliza- 

 tion. The dog at an early period had been his companion ; different 

 hoofed animals formed in his pastoral life his principal possession, 

 or his beasts of burden, which alleviated his necessary labour in 

 cultivating the land. 



Various is the abode (the physical distribution) of mammals. 

 Some reside entirely in the sea, as the cetaceans and most of the 

 seals (Phocce), although some species, especially of the animals last 

 named, live in fresh water. Many species of the genus Sorex, the 

 otters, beavers, the duck-mole, reside, in lakes and rivers. Other 

 mammals live under ground (Talpa, Bathyergus, &c.). The most 

 however live on land, some on high mountain tops (as Antilope 

 rupicapra, Copra Ibex), others on trees (most of the apes and 

 squirrels, the sloths), and some resort, by flying or flapping, in 



1 Compare on the auditory apparatus of mammals, besides the general works of 

 comparative anatomy, E. HAGENBACH Disquisitiones anat. circa, musculos auris internes 

 Hominis et Mammcdium, Basiliae, 1834, 4to; by the same, Die PaukenhoJile der Sauge- 

 thiere, Leipzig, 1835, 4to, and the eminent monography of J. HTRTL Vergleichend- 

 anatomiscJie Untersuchungen uber das innere Gehor- Oi'gan des Menschen und der Sduge- 

 thiere. Mit 9 Kupfertafeln. Prag, 1845, 4to. 



