TEETH AND THEIR VARIATIONS. 221 



part of Europe, extending as far north as the southern 

 parts of our own islands, and were also common in 

 Northern India; the same being true of the Giraffes, 

 with the exception that their remains have not hitherto 

 been found in Britain. 



The most complex type of teeth is, however, attained 

 by the Indian Elephant, and the closely allied Mam- 

 moth, which in the latest geological epoch ranged, over 

 the greater part of Europe, and whose frozen carcases 

 are from time to time washed out from the so-called 

 "tundras," or superficial deposits of Siberia, to be 

 exposed to human view after having been buried for 

 countless centuries. In these two species the plates of 

 the teeth are narrower and more numerous than in the 

 tooth represented in Fig. 77, so that the even surfaces 

 of dentine form still narrower stripes. At first sight it 

 seems difficult to believe that the Elephant now in- 

 habiting the burning plains of India should be closely 

 allied to a species which formerly roamed over the icy 

 regions of Siberia, but there are two considerations 

 which show how little value such objections have. 

 Thus, in the first place, there is considerable evidence 

 that the climate of Siberia, although doubtless always 

 cold in winter, was formerly less severe than at present. 

 We have, moreover, evidence in the case of the Tiger 

 how an animal can support the extremes of heat and 

 cold with no alteration of its structure. Many people, 

 indeed, if they were asked to mention the habitat of 

 the Tiger, would say India, little knowing that this 

 creature ranges in China and thence to Siberia into 



