New World monkeys are all tree dwellers, and many of them use their prehensile tails in traveling through forests. Among the New World monkeys are the capuchins, the howlers, and the spider monkeys. Spider monkeys have extremely long legs, arms, and tails, and can swing through the trees rapidly. They make sounds similar to the barking of a dog.

The sakis have shaggy fur and long, bushy tails. They have long, slender fingers on hands that resemble those of humans. Squirrel monkeys have facial markings that somewhat resemble human skulls. They are very noisy monkeys, constantly making squealing and chirping sounds.

Many New World monkeys are in danger. Some, such as muriquis and lion tamarins, are near extinction. Many New World monkeys have lost much of their habitat. People have cut down the trees in forests to get lumber and to clear land for farming. When monkeys lose their homes, they have nowhere else to go. \It is not easy for scientists to study some species of New World monkeys. Some live very high up in treetops. Other monkeys live in far off areas that are difficult to get to. Without knowing how some New World monkeys live, it is hard for scientists to learn how to protect them.

Even today, scientists are discovering new species. And they are gradually learning more and more about how other New World monkeys live. As people get to know about New World monkeys, it is hoped that they will be able to protect these animals and their habitats.

Monkeys belong to the order Primates.

Old World monkeys make up the family Cercopithecidae. This family includes the guenons (genus Cercopithecus), mangabeys (Cercocebus), macaques (Macaca), drills and mandrills (MandrIllus), baboons (Papio), colobus monkeys (Colobus), and proboscis monkeys (Nasalis).

Marmosets, according to most taxonomists, make up the family Callithrichidae. Some taxonomists place Goeldi's marmoset, Callimico goeldii, in the family Callimiconidae. Other New World monkeys belong to the family Cebidae. It includes the howler monkeys (genus Alouatta), spider monkeys (Ateles), squirrel monkeys (Saimiri), capuchins (Cebus), and sakis (genera Pithecia and Chiropotes).