Chap. V. DISTRIBUTION OF MONKEYS. 329 



tute of monkeys, and why should Madagascar have 

 stopped short at Lemurs, whilst America has gone on 

 to prehensile-tailed Cebidae, and the Old- World con- 

 tinent continued to Gibbons, Orangs, Chimpanzee, and 

 Gorilla ? Is it that the greater land masses have seen 

 a larger amount of geological and climatal changes with 

 corresponding changes in the geographical relations of 

 species ? Moreover, why should the smaller groups of 

 the order be confined to smaller areas within the greater 

 areas peopled by the families to which they belong? 

 For, it must be added, the true Lemurs are confined to 

 Madagascar, the Gibbons and others to South Eastern 

 Asia, the dog-faced baboons to Africa, and, as we have 

 seen, the scarlet-faced monkeys to a limited area on the 

 Upper Amazons. May we be allowed to explain the 

 absence of these animals from New Guinea with Aus- 

 tralia, by the supposition that those lands were separated 

 from South Eastern Asia before the first forms of the 

 order came into existence ? If so, it may be concluded 

 that Madagascar became separated from Africa, and 

 America from the continental mass of the old world 

 before the Pithecidas originated. But, if these explana- 

 tions, founded on natural causes, be entertained, we 

 commit ourselves, by the fact of entertaining them, to the 

 admission that natural causes are com pe tent to explain 

 the existence or non-existence of forms in a given area, 

 and why may not the exercise of our reason, founded on 

 carefully observed and collated facts, be carried a step 

 farther, namely to the origin of the species of monkeys 

 themselves? I have already shown how singularly 

 species of monkeys vary in different localities, and have 



