DISTRIBUTION OF MONKEYS 455 



Is it that the greater land masses have seen a larger 

 amount of geological and climatal changes with corre- 

 sponding 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 Australia, 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 se- 

 parated from Africa, and America from the continental 

 mass of the old world before the Pithecidae originated. 

 But, if these explanations, founded on natural causes, be 

 entertained, we commit ourselves, by the fact of enter- 

 taining them, to the admission that natural causes are 

 competent 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 given the striking case of the white 

 and red-haired Uakarls. If these two forms, which are 

 considered by the most eminent naturalists as distinct 

 species, have originated, as the facts of their distribution 

 plainly tell us they have, from one and the same stock, 

 why may not the various species of Lemurs, of Baboons, 

 of Gibbons, and so forth, given the necessary amount of 

 time and climatal changes, have originated in the same 

 way ? And if we can thus account for the origin of the 

 species of one genus, on what grounds can we deny that 

 the genera of the same family, or the families of the same 

 order, have also proceeded from a common stock ? I 

 throw out these suggestions simply for the consideration 

 of thoughtful readers, but must add, that unless the 

 common origin, at least, of the species of a family be 

 admitted, the problem of the distribution of monkeys 

 over the earth's surface must remain an inexplicable 

 mystery, whilst, if admitted, a flood of light illuminates 



