The possessor of these curious appendages, whatever Howler it may be, for all the species of the genus have them, is active enough in his woods, but still is a sad-looking animal, much given to crawling listlessly from branch to branch, and becoming melancholy in captivity. They have a surly disposition, are never to be made pets of, and are savage; while at the same time they show none of the lively play which makes the Spider Monkeys and little Sapajous so very amusing. Possibly their howling exhausts much of their nervous energy, and certainly their brains are peculiar. The back, or occipital part of the brain, does not cover the cerebellum, or little brain, which is large in proportion to the rest. The brain is small in comparison with those of the other American Monkeys, due allowance being made for the greater size of the Howler; and its surface markings or convolutions are few and simple. There is much less brain-matter packed up in folds, or convolutions, than in most Monkeys, and some of the most important are wanting (the angular and external perpendicular), and it has a shrunken and contracted look. Everything shows a low condition of intelligence and mental power. The absence of so much brain-matter behind, so unusual amongst the Monkeys, has suggested to those who believe in phrenology that the bump of philo-progenitiveness was absolutely deficient in this species. But in spite of this, we find that the Howlers are kind to each other, and bring up their solitary little ones, teaching and feeding them with just the same amount of affection that all the other New World kinds display. So the love of offspring is not deficient; nevertheless, it may be assumed that the sameness of habits and the slight requirements of their lives render a more elaborate brain unnecessary. Finally this and all the Howlers have the stomach a little disposed to be arranged as more than one single sac, and in this there is just the hint of the condition in the Semnopitheci of the Old World. THE BLACK HOWLER.[79]