182 ESSAY ON CLASSIFICATION. 



show animals make almost everywhere. And yet it will, 

 perhaps, some day be easier to understand the relations 

 existing between the geographical distribution of animals 

 and the other general relations prevailing among animals, 

 because the range of structural differences is much greater 

 among animals than among plants. Even now, some 

 curious coincidences may be pointed out, which go far to 

 show that the geographical distribution of animals stands 

 in direct relation to their relative standing in their re- 

 spective classes, and to the order of their succession in 

 past geological ages, and more indirectly also to their em- 

 bryonic growth. 



Almost every class has its tropical families, and these 

 stand generally highest in their respective classes ; or 

 when the contrary is the case, when they stand evidently 

 upon a lower level, there is some prominent relation be- 

 tween them and the prevailing types of past ages. The 

 class of Mammalia affords striking examples of these two 

 kinds of connection. In the first place, the Quadrmnana, 

 wdiich, next to Man, stand highest in their class, are aU 

 tropical animals ; and it is worthy of remark that the two 

 highest types of Anthropoid Monkeys, the Orangs of Asia 

 and the Chimpanzees of Western Africa, bear, in the colo- 

 ration of their skin, an additional similarity to the races 

 of Man inhabiting the same regions, the Orangs being 

 yellowish red, as the Malays, and the Chimpanzees blackish, 

 as the Negroes. The Pachyderms, on the contrary, stand 

 low in their class, though chiefly tropical ; but they con- 

 stitute a group of animals prominent among the earliest 

 representatives of that class in past ages. Among the Chi- 

 roptera the larger, frugivorous representatives are essen- 

 tially tropical ; the more omnivorous, on the contrary, 

 occur everywhere. Among the Carnivora the largest, most 



