Perhaps the most curious of all the American monkeys are the spider-monkeys, which look very much like big black spiders when one sees them gamboling among the branches of the trees. The reason is that their bodies are very slightly built, and their arms and legs are very long and slender, while the tail is often longer than the head and body together, and looks just like an extra limb. And indeed it is used as an extra limb, for it is prehensile; that is, it can be coiled round any small object so tightly as to obtain a very firm hold. A spider-monkey never likes to take a single step without first twisting the tip of its tail round a branch, so that this member really serves as a sort of fifth hand. Sometimes, too, the animal will feed itself with its tail instead of with its paws. And it can even hang from a bough for some little time by means of its tail alone, in order to pluck fruit which would otherwise be out of its reach. Owing partly, no doubt, to constant use, the last few inches of this wonderful tail are quite bare underneath--without any hair at all. It is worth while to remember, just here, that while in many American monkeys the tail has this prehensile grasp, no monkey of the Old World is provided with this convenience. When a spider-monkey finds itself upon level ground, where its tail, of course, is of no use to it, it always seems very uncomfortable. But it manages to keep its balance as it walks along by holding the tail over its back, and just turning it first to one side and then to the other, as the need of the moment may require. It uses it, in fact, very much as an acrobat uses his pole when walking upon the tight rope. It is rather curious to find that while other monkeys are very fond of nibbling the tips of their own tails, often making them quite raw, spider-monkeys never do so. They evidently know too well how useful those members are to injure them by giving way to such a silly habit--which is even worse than biting one's nails. When a spider-monkey is shot as it sits in a tree, it always coils its tail round a branch at once. And even after it dies, the body will often hang for several days suspended by the tail alone. These monkeys spend almost the whole of their lives in the trees, feeding upon fruit and leaves, and only coming down to the ground when they want to drink. As a general rule they are dreadfully lazy creatures, and will sit on a bough for hours together without moving a limb. But when they are playful, or excited, they swing themselves to and fro and dart from branch to branch, almost as actively as the gibbons. HOWLERS