feet, the digits of which are armed with claws, and the posterior members presenting only imperfect hands. The head is roundish; the flat face is animated with small but very bright eyes; the ears are often adorned with tufts of hair, which give an odd character to the physiognomy. Finally, the body is covered with a thick coat of soft, silken hair, often with regularly-arranged bands in the back and tail. By
their aspect, and the coloration of their fur, by their size, by their mode of life, as also by the details of their organization, the Hapalians constitute a very natural family. Still, they may be divided into two genera, the Uistitis (Hapale or Jacchus), with long, tufted tail, with no fringe of hair around the face, but with tufts of hair on the ears; and the Tamarins (Midas), whose head is adorned with a fringe, but whose ears are more or less denuded. We will set this latter group completely aside, and consider only the Uistitis.
The species of the genus Jacchus, all, without exception, are found in tropical America, between the Isthmus of Panama and latitude 30° south, but chiefly, if not exclusively, in the region lying to the east of the Andes, some of them inhabiting the virgin forests, others the thickets scattered over the plains. The best-known species is the common Uistiti (Hapale or Jacchus vulgaris), with gray-russet pelt, with alternate red and blackish streaks, and with from fifteen to eighteen rings on the tail, a white, triangular spot on the forehead, and long white hairs on the sides of the head. It is a native of Guiana and Brazil, and
- The name Hapalians, given to these monkeys by Illiger, is derived from the Greek ἁπαλός, which means soft.