CHAPTEE IV 



GEOGRAPHICAL AND GEOLOGICAL DISTRIBUTION 

 I. GEOGRAPHICAL DISTRIBUTION. 1 



IN considering the present distribution of mammals over the 

 globe, we may, in the first place, direct our attention to terrestrial 

 or land types, reserving the consideration of aerial types, like the 

 Bats, and aquatic forms, as exemplified by the Cetaceans, Sirenians, 

 and Seals, to separate sections. 



Among terrestrial forms each species has a certain definite area 

 of distribution in space, which may be of very wide extent, or may 

 be confined to a restricted region. This distributional area is, 

 however, always connected, or continuous; that is to say, that 

 although we may have a single species inhabiting two continents, 

 like the Lion in Asia and Africa, or dwelling both on a continent 

 and adjacent continental islands, like the Javan Rhinoceros of India, 

 Java, and Borneo, yet we shall always find that such areas, if not 

 still connected, show evident signs of having been so connected 

 in comparatively late geological epochs ; and we never find 

 instances of the same species inhabiting totally disconnected areas, 

 such as India and South America. As examples of mammals 

 with a wide distribution we may mention the Lion and the 

 Leopard, which are now found throughout Africa, and also occur 

 in India, as well as in the intervening areas of Arabia and Persia. 

 In the case of the former species, palaeontology further teaches us 

 that its distribution in the last geological epoch was even more 

 extensive, since we have good evidence to show that it formerly 

 ranged over the greater part of Europe, including the British Isles. 

 The Jackal affords another well-known instance of a species common 



1 On this subject see A. Murray, Geographical Distribution of Mammals, 1866 ; 

 and especially A. R. Wallace, The Geographical Distribution of Animals, 2 vols., 

 1876, and Island Life, 1881 ; also A. Heilprin, The Geographical and Geological 

 Distribution of Animals, 1887. 



