Page:The naturalist on the River Amazons 1863 v2.djvu/345

 be interesting, therefore, to see how differently the subsequent creations of species have proceeded in each of the separated areas.

The American monkeys are distinguished, as a body, from all those found in the Old World. Upon this point, there is no difference of opinion amongst modern zoologists. It is not probable, therefore, that species of the one continent have passed over to the other, since these great tracts of land received their present inhabitants of this order. The American productions present a cluster of forms, namely, about eighty-six species, separated into thirteen genera, which although greatly diversified amongst themselves, in no case show signs of near relationship to any of the still more diversified forms of the same order belonging to the eastern hemisphere. One of the two American families (Cebidæ) has thirty-six teeth, whilst the corresponding family (Pithecidæ) of Old World apes has, like man, only thirty-two teeth; the difference arising from the Cebidæ having an additional false molar tooth to each side of both jaws. This important character is constant throughout all the varied forms of which the Cebidæ family is composed; being equally present in the prehensile-tailed group, with its four genera containing twenty-seven species, differing in form and clothing, shape of claws, mental characteristics, and condition of thumb of the anterior hands; and in the true Cebi and the group of Sagouins, with six genera and twenty-four species, including day apes and night apes, short