CHAP. XIX THE MADAGASCAR GROUP 421 



these cases we have ample proof of the former wide 

 extension of the group. Extinct camels of numerous 

 species abounded in North America in Miocene, Pliocene, 

 and even Post-pliocene times, and one has also been found 

 in North-western India, but none whatever among all the 

 rich deposits of mammalia in Europe. We are thus told, 

 as clearly as possible, that from the North American con- 

 tinent as a centre the camel tribe spread westward, over 

 now-submerged land at the shallow Behring Straits and 

 Kamschatka Sea, into Asia, and southward along the 

 Andes into South America. Tapirs are even more inter- 

 esting and instructive. Their remotest known ancestors 

 appear in Western Europe in the early portion of the 

 Eocene period ; in the latter Eocene and the Miocene other 

 forms occur both in Europe and North America. These 

 seem to have become extinct in North America, while in 

 Europe they developed largely into many forms of true 

 tapirs, which at a much later period found their way again 

 to North, and thence to South, America, where their 

 remains are found in caves and gravel deposits. It is an 

 instructive fact that in the Eastern continent, where they 

 were once so abundant, they have dwindled down to a 

 single species, existing in small numbers in the Malay 

 Peninsula, Simiatra, and Borneo only; while in the 

 Western continent, Avhere they are comparatively recent 

 immigrants, they occupy a much larger area, and are re- 

 presented by three or four distinct species. Who could 

 possibly have imagined such migTations, and extinctions, 

 and changes of distribution as are demonstrated in the 

 case of the tapirs, if we had only the distribution of the 

 existing species to found an opinion upon ? Such cases as 

 these — and there are many others equally striking — show 

 us with the greatest distinctness how nature has worked 

 in bringing about the examples of anomalous distribution 

 that everywhere meet us ; and we must, on every ground 

 of philosophy and common sense, apply the same method 

 of interpretation to the more numerous instances of 

 anomalous distribution we discover among such groups as 

 reptiles, birds, and insects, where we rarely have any direct 

 evidence of their past migrations through the discovery of 



