Animals which feed upon vegetables, and live on the high mountains of Asia and Africa, produce the oriental bezoar, the virtues of which are so highly extolled. The animals of the mountains of Europe, where the qualities of the plants are more temperate, only produce the _ægagropili;_ and in South America those animals which dwell upon the mountains of the torrid zone, afford another kind of bezoar, called _occidental_, more solid, and perhaps possessing greater virtues than the _oriental_. The wild pacos produces it in great quantities, as do the huanacus; and it is also extracted from the stags or roe-bucks of New Spain. The lamas and the pacos afford the best bezoar when in their natural or wild state: those produced in their state of slavery are small, black, and of but little or no virtue. The best bezoars are those of a dark green colour, which commonly proceed from the wild pacos, especially those which feed in the snow on the tops of the mountains. Of these, both the male and female produce bezoars; and these Peruvian bezoars are the next in rank to the oriental, and are much more esteemed than those of New Spain, which are produced by stags, and are the least efficacious of any. THE UNAU, OR FOUR-TOED, AND THE AÏ, OR THREE-TOED, SLOTHS. These two animals have had the name of _Sloths_ given to them on account of their slowness, and the difficulty with which they walk. Though they resemble each other in many respects, nevertheless they differ externally and internally by such strong characters that it is impossible to mistake the one for the other, or doubt of their being very distinct species. The unau (_fig. 166._) has no tail, and only two claws on the fore feet. The aï has a short tail, and three claws on each foot. The nose of the unau is likewise longer, the forehead higher, and the ears larger than the aï. They differ also in the hair. Some parts of their viscera are formed and situated different; but the most distinct and singular character is, the unau has forty-six ribs; and the aï but twenty-eight; this alone proves them to be two species quite distinct from each other. These forty-six ribs in an animal whose body is so short is a kind of excess, or error, in nature; for even in the largest animals, and those whose bodies are relatively longer than they are thick, not one of them is found to have so many; the elephant has only forty, the horse thirty-six, the badger thirty, the dog twenty-six, the human species twenty-four, &c. This difference in the construction of the sloths supposes a greater dissimilitude between these two species than there is between the cat and dog, both of which have the same number of ribs. External differences are nothing in comparison with internal ones. The internal frame of living animals is the groundwork of Nature's design, it is the constituent form, and the cause of all figure; and the external parts are only the surface or drapery.