CHAP. XIX.] 



THE MADAGASCAR GROUP. 



31)3 



southward along the Andes into South America. Tapirs are 

 even more interesting and instructive. Their remotest known 

 ancestors appear in Western Europe in the early portion of the 

 Eocene period ; in the later 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 mueh 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, Sumatra, and Borneo only ; while in 

 the Western continent, where they are comparatively recent 

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

 sented by three or four distinct species. Who could possibly 

 have imagined such migrations, 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 w^e discover among such groups as reptiles, birds, 

 and insects, where we rarely have any direct evidence of their 

 past migrations through the discovery of fossil remains. When- 

 ever we can trace the past history of any group of terrestrial 

 animals, we invariably find that its actual distribution can be 

 explained by migrations effected by means of comparatively 

 slight modifications of our existing continents. In no single 

 case have we any direct evidence that the distribution of land 

 and sea has been radically changed during the whole lapse of 

 the Tertiary and Secondary periods, while, as we have already 

 shown in our fifth chapter, the testimony of geology itself, if 

 fairly interpreted, upholds the same theory of the stability of 

 our continents and the permanence of our oceans. Yet so easy 



