82 ZOOLOGICAL GEOGRAPHY. [part hi. 



Carnivora. Later, it received its Camelidae, peccaries, mastodons, 

 and large Carnivora; and later still, just before the Glacial 

 epoch, its deer, tapir, opossums, antelopes, and horses, the two 

 latter having since become extinct. All this time its surface 

 was undergoing important physical changes. What its earlier 

 condition was we cannot conjecture, but there are clear indica- 

 tions that it has been broken up into at least three large masses, 

 and probably a number of smaller ones ; and these have no 

 doubt undergone successive elevations and subsidences, so as 

 at one time to reduce their area and separate them still more 

 widely from each other, and at another period to unite them 

 into continental masses. The richness and varied development 

 of the old fauna of South America, as still existing, proves, how- 

 ever, that the country has always maintained an extensive area ; 

 and there is reason to believe that the last great change has 

 been a long continued and steady increase of its surface, 

 resulting in the formation of the vast alluvial plains of the 

 Amazon, Orinoko, and La Plata, and thus greatly favouring 

 the production of that wealth of specific forms, which dis- 

 tinguishes South America above all other parts of our globe. 



The southern temperate portion of the continent, has probably 

 had a considerable southward extension in late Tertiary times ; 

 and this, as well as the comparatively recent elevation of the 

 Andes, has given rise to some degree of intermixture of two 

 distinct faunas, with that proper to South Temperate America 

 itself. The most important of these, is the considerable Austra- 

 lian element that appears in the insects, and even in the reptiles 

 and fresh-water fishes, of South Temperate America. These may 

 be traced to several causes. Icebergs and icefloes, and even 

 solid fields of ice, may, during the Glacial epoch, have afforded 

 many opportunities for the passage of the more cold-enduring 

 groups; while the greater extension of southern lands and 

 islands during the warm periods — which there is reason to 

 believe prevailed in the southern as well as in the northern 

 regions in Miocene times — would afford facilities for the passage 

 of the reptiles and insects of more temperate zones. That no 

 actual land-connection occurred, is proved by the total absence 



