In addition to the absence of prehensile power in their tails, douroucoulis, also known as night-apes, are distinguished by their large eyes, the sockets of which occupy nearly the whole front of the upper part of the skull, the partition between the nostrils being in consequence narrower than usual.
Douroucoulis live in parties, and are purely nocturnal, sleeping during the day in hollow trees, and coming out at night to feed on insects and fruits, when they utter piercing cat-like screams.
The squirrel-monkeys were formerly classed with the douroucoulis (see DouRoucouLI), but, on account of their brain-structure, they have been transferred to the Cebinae (see CAPUCHIN-MONKEY), from the other members of which they differ by their practically non-prehensile tails and smaller size, while they are further distinguished by their comparatively large eyes and the backward prolongation of the hinder part of the head.