246 THE DOCTRINE OF DESCENT. 



and Weddell, from the Brazilian caves, and the alluvium 

 of the Pampas, among the 118 species cited, actually 

 includes, in addition to those already mentioned, as be- 

 ing of probably Old-World pedigree, no less than 35 

 species of Edentata, and these animals of consider- 

 able bulk. Not reckoning the 36 rodents and bats, and 

 the smaller fauna in general, they constitute nearly half 

 of the larger diluvial animals of South America. The 

 assemblage of Edentata previously settled in these 

 regions thus held their own against the invasion from 

 the north. 



"It is comprehensible that the same external causes 

 which led the march of the children of the north con- 

 stantly further, may likewise have invited the members 

 of the antarctic fauna to extend themselves northwards. 

 As we even now encounter the incongruous forms of 

 the sloth, the armadillo, and the ant-eater in Guatemala 

 and Mexico, in the midst of a fauna in great part con- 

 sisting of races still represented in Europe, we also find, 

 even in diluvial eras, gigantic sloths and armadillos rang- 

 ing far into the north. Megalonyx Jeffersoni, and Mylo- 

 don Harlemi, sentries of South American origin thrown 

 out as far as Kentucky and Missouri, are a phenomenon 

 as heterogeneous in the land of the bison and the deer, as 

 is the mastodon in the Andes of New Granada and Bo- 

 livia. Over the whole enormous extent of both portions 

 of the New Continent, the mixture and interpenetration 

 of two mammalian groups of completely diverse families, 

 constitutes the most conspicuous feature of its fauna ; and 

 it is significant that each group increases in the abundance 

 of its representatives and in the originality of their ap- 

 pearance as we approach its point of derivation." 



