From its fierce countenance, long, sharp teeth, and savage temper, it has gained its second scientific name Brachyuras Satanus. The cacajao is a curious contrast to the cuxio. It is called also the black-headed saki. Unlike most of its brethren, it has but a short, hairy tail, looking as if it had been docked.

Although he might easily draw out his hand by opening it, this he does not think of doing; and thus, unable at the best to move rapidly over a level surface, is soon overtaken by the hunter, and captured. Among the host of curiously-shaped, long-tailed, active little monkeys which inhabit the American forests, the cuxio is one of the most remarkable.