ANATOMY OF THE HOWLER. 
169 
complicated by air sacs and resounding chambers. The breast-bone of the Howler differs in certain 
respects from that of all other Monkeys, for its upper bone (manubrium) is halved, and each half 
supports the end of the collar-bone and first rib. Possibly the resulting space may ha ve something 
to do with the air sacs. 
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 
YELLOW- TAILED HOWLER AND YOUNG. 
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 pliilo-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. 
