Spider-monkey, a name given to an American genus of monkeys, Ateles. These monkeys have no thumb, or it is rudimentary. They occur only in South America, Mexico, and Central America. The popular name has been given to them on account of their long, slender limbs. Like other New-World monkeys (Platyrrhini), they have a prehensile tail, and are naturally purely arboreal in habit. Although denizens of the tropical forests of the New World, they can, like the tropical apes of the Old World, endure a very considerable amount of cold. One species, A. vellerosus, lives in large companies in forests at a height of 7000 feet in Mexico. The Coaita is the A. paniscus. About fourteen species of the genus are known.