FATJNAL VARIATION. 5 



familiar types have either wholly disappeared, or are fast disap- 

 pearing. Such may be the musk-sheep, moose, stag, and reindeer, 

 which will have left as their successors the bisons and the various 

 species of smaller deer which range throughout the remainder of 

 the continent. The grey wolf of the northern forests breaks up into 

 a number of varietal forms more or less distinct from the typical 

 one, and is carried by the coyote into the heart of Mexico. 



Farther to the south the traveller observes entirely new features 

 gradually appearing. In Arkansas he possibly meets with the pec- 

 cary, the first indigenous member of the pig family with which he 

 will have become acquainted; in Texas, with the armadillo, the 

 first of that group of animals, the Edentata, which, in the past and 

 present history of the South American continent, constitutes such 

 an important element in its fauna ; and, in the States adjoining the 

 Mexican Republic, with an abundant representation of the iguanid 

 lizards, which, by their numbers, so eminently typify the follow- 

 ing region of the tropics. There are as yet neither monkeys, ta- 

 pirs, nor guinea-pigs, but the first appear in Southern Mexico, the 

 second in Central America, and the last in Venezuela or Guiana. 

 The traveller is now in the region of the Equator, and surrounded 

 by an association of animal forms most of which were unknown to 

 him when he entered upon his journey, and which in many respects 

 depart so widely from those with which he was familiar at his start- 

 ing-point as to constitute a distinct fauna. There is no longer 

 either wolf, fox, or catamount, beaver or musk-rat, and of the spe- 

 cifically important group of the hares or rabbits but a single species 

 remains. The solitary species of bear is so different from its north- 

 ern cousins as to be regarded by some naturalists as the type of a 

 distinct genus. 



The contrast between the successive faunal changes observed on 

 the north and south journey and the faunal identity which so aston- 

 ishes the traveller whose journey is directed eastward from Eng- 

 land to' Japan is very great. And yet if the traveller from Britain, 

 instead of proceeding due eastward, were to shape his course a 

 few degrees to the south, much the same kinds of changes as he 

 noticed on his American trip would again present themselves. 

 Along the shores of the Mediterranean he would no longer, or only 

 at rare intervals, meet with his associates of the Arctic north; on 

 the southern slopes of the Caucasus the tiger, and in Arabia the 



