78 GEOGRAPHICAL RANGE chap. 



Altogether the enormous progress in the complexity of the 

 brain from the early Tertiary mammals down to the present, is 

 one of the most remarkable revelations of palaeontology. It 

 goes perhaps some way in explaining the remarkable diversity 

 in mode of life exhibited l^y the mammals as compareil, for 

 example, with the birds, whose brains have not diverged so much 

 or in so many directions from the primitive form. 



The present Distribution of the Mammalia. — In the foUoAv- 

 ing pages some of the principal facts in the geographical range 

 of the orders, families, and many of the genera of Mammalia 

 will be given. It has been justly observed by ilr. Sclater 

 that the habitat of an animal is as much a part of its 

 definition as is its structiire or external form. No systematic 

 account of the ilaramalia would therefore be complete without 

 such geographical facts. But that branch of zoology which 

 is concerned with the past and present distribution of animals 

 is wider in scope than this. Zoogeography deals not only 

 with the actual facts in the range of animals, but with the 

 inferences as to past changes in the relations of land and sea 

 which the facts seem to indicate, and with speculations as to 

 the place of origin of the different groups, of which more than 

 hints are sometimes given by their past and present distribution. 

 In addition to this, the earth can be mapped out into provinces 

 and regions which are definable Ijy their animal inhabitants. 

 In the present volume, dealing only with the Mammalia, it will 

 be obviously impossible to enter full)' into the entire subject 

 of zoogeography. All that will be attempted is a brief general 

 survey of the science so far as it can be illustrated by the 

 Miimmalia. For fuller knowledge the reader is referred to the 

 treatises mentioned below. ^ 



There are certain facts in the distribution of animals which 

 are commonplaces of knowledge, but which nuiy be set forth 

 with definiteness. Everybody knows that an animal has a given 

 range : Elephants, for example, are found in India and certain 

 adjacent parts of Asia, and again in Africa ; the Ehinoceroses 

 have roughly the same range ; the Tiger is limited to Asia ; the 



' Wallace, The Geographical Distribution" of Animals, 1876. Heilprin, The 

 Distribution of Animals, Internat. Scientific Series, 1887. Beddard, A Text-book 

 of Zoocjeography, Cambridge Natural Science Manuals, 1895. Lydekker, Geographi- 

 cal History of Mammals, Camljridge Geographical Series, 1896. W. L. and P. L. 

 Sclater, The Geograpihy of Mammals, Kegan Paul and Co. 1899. 



