Page:Natural History (1848).djvu/39

Rh anterior thumbs (using the ordinary expression for them) are placed absolutely on the same line with the other fingers, are of the same form with them, act invariably in the same direction, and are totally incapable of being opposed to them. In the two remaining genera, Cebus and Callithrix, the extremities of the anterior limbs have a greater resemblance to the hands of Man, and of the Monkeys of the Old World:—the internal finger is placed farther back than the general line of the other fingers, and has, on that account, when superficially noticed, the semblance of being opposed to them: but, as has been correctly observed by D’Azara, with reference to ''Call. capucinus'', it is less separated than in Man; it is, besides, of precisely the same slender form with the rest, is weaker than they, absolutely without power of opposition to them, and habitually acts in the same direction with them. The impression derived from contemplating the hands of the Old World Monkeys, might induce the belief that the extremities of the Cebi are similarly constituted; but if the knowledge that in Mycetes, Pithecia, &c., there are no opposible thumbs, leads to a close observation of the anterior extremities of the Cebs, it will be found that they do not act as hands, and cannot be considered as possessing the powers of those organs.”

The Cebidæ are confined to the hotter parts of the Southern American continent, and inhabit the dense forests.

In this genus, which comprehends the largest and fiercest of the American Monkeys, the hyoid