They have rather tall heads, with beard and large lower jaws, which, with a thickness about the throat, give the appearance of an unusual swelling being there, the cause of which will be noticed further on. Some have long and others short fur, but generally there is much of it about the head (where it is brushed forwards) and neck. Black and red are favourite colours, and the young of both sexes differ often in their tints from the adults, and so do the males from the females. One kind in particular is decidedly coloured.
THE YELLOW-TAILED HOWLER.[78]
The last half of the tail of this species is of a brilliant golden-fawn colour, and this tint is on the upper parts of the body nearly up to the shoulders; the rest of the tail is light maroon, and what remains of the body is dark maroon, there being a violet tint in the limbs.
Besides its colours this kind presents some points of interest. They live in companies, and when they pass from one tree to another they all play at follow-my-leader exactly. They watch the movements of those which precede them, jump in the same manner, and at the same place, and even place their feet and hands on the same spots on the boughs. They are found in Columbia and New Granada, and in Brazil on the confines of Paraguay.
BONES OF THE TAIL
OF THE HOWLER.
The limbs of all the Mycetes are long, and whilst there is a good toe-thumb to the foot, the very best of the hand-thumbs is not equal to those of the Monkeys of the Old World. The nails on the fingers and toes are compressed from side to side, as it were, and begin to look like claws.
Ogilby, an admirable observer, noticed years ago that two Howlers did not use their hands so as to take things between the thumb and forefinger, and he ascertained that this thumb was so much on a line with the other fingers that it was not opposable in the ordinary sense of the word, and that it was more like an extra finger than a thumb. This, he noticed, was not the case with the Howlers alone, but that it peculiarised the Monkeys of the New World. The examination of their skeletons shows that the bones of the thumb are on the same plane or level as the fingers, and the whole is brought close to the fingers, as our great toe is to the other toes. Nevertheless, this thumb can move to and from the fingers.
But if the fore-hand so greatly resembles a paw, compensation is made to the animal by the gift of the prehensile tail, which is very muscular, and the under surface is without hair near the end, so that the sensitive surface can touch and feel objects. They can feel, therefore, around them, and also above them, as they move along and lay hold of branches and hanging creepers without looking for them. The delicate sense of feeling depends on the nervous supply; and the power of clasping and holding on upon the bending or flexor muscles. A bony framework supports all these structures, and runs from the last bone of the sacrum to the tip, and consists of many separate vertebral bones placed in a long series. The first few bones which join on to the sacrum, and form the root of the tail, resemble the back-bone pieces, or vertebræ, to a certain extent. Each has a body, and also processes for jointing with the one before and behind, and a spine also. Besides these, there are two curious projections on the lower part of each body, which are called chevron bones, and are V-shaped, and their use is to allow the blood-vessels and nerves to pass along between them without being pressed upon. Towards the end of the tail the vertebræ become long and stout, and are united behind and in front, forming a broad bone, and without the joints, and the chevron bones are reduced to little rounded pieces of bone. Everything tends in this tail to ready, rapid, and forcible motion, and indeed so perfect an organ is it that when one of these Howlers is shot it always hangs to the tree by its tail, even if quite dead, and does not fall down until some hours afterwards, when the strong flexor muscles have relaxed. Therefore, writes a recent author, if fresh food is required, it is best to kill a Lagothrix (see [page 171]) in the Peruvian valleys, as hung meat soon becomes tainted. The Golden Howler, nevertheless, furnishes the principal animal food to the inhabitants of the banks of some of the rivers entering the Peruvian Amazon. They keep to the low lands and shores of the rivers, and are found moving from place to place in pairs.
