The Chacmas are found in great troops, and they behave very much after the manner of the other large Baboons, their strength rendering them a terror to the Dogs of the colonists. In ascending the kloofs, or passes, in the mountains of South Africa, which are frequently steep, narrow, and dangerous, travellers often disturb great troops of these animals, which have been sunning themselves on the rocks. If not attacked they scamper up the sides of the mountains yelling and screaming. They resent being fired upon by rolling down stones. The Chacma has a fine black tail, which is rather more than half the length of the body, and it has a tuft of long black hair at its tip. It is carried like that of the other long-tailed Baboons, being curved upwards at first, and then falling down straight. Nearly all the fur of the body is a uniform dark brown, almost black, mixed throughout with a dark green shade. It is long and shaggy, particularly on the neck and shoulders of the males. If a solitary hair be pulled out, it will be found to be very curiously ornamented. It has a root, like all hairs, springing from a little pimple under the scarf-skin, and its colour is at first of a light grey colour. Then it is marked with wide rings of colour, which are perfectly distinct, and they are alternately black and dark green, but sometimes they are intermixed with a few of a lighter or yellowish shade. The face and ears are naked, as are also the palms and soles, and there are small whiskers, grey in colour and brushed backwards. Naked as are the face, ears, and hands, the skin is of a very dark violet-blue colour, with a pale ring surrounding each eye. Strange to say, the upper eyelids are white. In the adult the muzzle is very long in comparison with the skull, which is greatly flattened and contracted; but in the young, the size of the nose is not so apparent, and the head is rounder, and the brain case is larger in proportion. As age comes on, the brain is not increased in size correspondingly with the face.