TEE SETTER MONKEYS. 
172 
But on examining the hands carefully, and noticing the deep parts as well as the outside, it was 
found that they could be ranged into two sub-groups. In one there is no external appearance of 
a thumb, and in the other there is a stunted projection, but in both the member is not quite 
deficient so far as its bones are concerned. In the first group the metacarpal bone (the bone which 
is in man covered by the ball of the thumb, and which extends from the wrist to the first joint) 
is just seen, but it does not project ; and in the second group there is one phalanx or tliumb-bone on 
the metacarpal, and this sticks out and is covered with skin so as to resemble a hard pimple. In one 
kind this little thumb has no nail, and in another there is one on it. 
It is curious that some of the woolly-haired kinds of Ateles should have no thumbs and others 
their rudiments ; and that this should be the case in the long and harsli-haired kinds also. There 
are many kinds of Ateles, and there is consequently some difficulty in recognising them as species, 
and many attempts have been made to classify them, so that they might be readily distinguished. 
Those with short and thick thumbs have been called Bracliyteles, 
and those without them Ateles ; those with woolly fur have been 
termed Eriodes, but all are now included in the genus Ateles. 
Everybody is interested in seeing the curious sprawling 
swinging of the Ateles in the Zoological Gardens, and also in 
noticing the curious way in which some can place their hand 
right over the head nearly on to the opposite shoulder, and brush 
the hair with it forwards, and especially because both kinds of 
movement refer to the great length of the fore-limbs. On the 
contrary, although they can maintain the erect posture for a 
short time, they seem feeble about the hind limbs, which are 
shorter than the others. Their lieel-bones are evidently short, so 
that leaping is never w r ell done. 
They are fruit and vegetable eaters, and enjoy eggs, and a 
nut occasionally, but they have no cheek-pouches. They have, 
however, an air-poucli, or sac, in front of the throat, but none 
of the noise-making gifts of the Howlers, and this sac enters 
the windpipe differently to those of the Monkeys of the Old World, and this is very curious. It 
opens into the windpipe below the cartilage which forms the 44 Adam’s apple ” in man, and not above 
and between it and the tongue. Below this cartilage, which is called the thyroid cartilage, there is 
another attached to it by which it joins on to the rings of the windpipe. The opening is between 
this lower cartilage, the cricoid, * and the top ling of the windpipe. 
Their stomach is single, and the large intestine, as they are vegetarians, is large, and its termi- 
nation the 44 ere cum ” also, but it has no little worm-like appendage as in the Gibbons. No especial 
points have been noted in the muscular system, except the very curious fact that, although the bones 
of the thumb are so rudimentary, the muscles are all there except the one which principally 
bends it forward. 
As the activity of the Spider Monkey is marvellous, as they swing on and catch hold of boughs 
with great skill and energy, and as they display much intelligence, their brains ought to be well 
developed. Doubtless there is a great deal of movement in these long-limbed creatures which takes 
place like the walking of man, i.e., without direct thought, for we move our leg muscles, and all those 
which assist them in the act of walking, without a constant direction of the will. Just as man s 
walking is thus said to be done automatically, so much of the swinging and progression of the Ateles 
is produced without direct exertion of the will. But it is evident that the Spider Monkey judges 
his distance, and very often considers whether such and such a bough will bear his weight, and uses 
exactly sufficient muscular exertion for -what he requires. 
Moreover, there is a graceful co-ordination or mutual action of the muscles of the limbs, body , and 
tail to a common end in most of its movements which are evidently done by will. The movements of 
the tail are perfectly wonderful, and, indeed, so perfectly does it hold on, although the animal cannon 
BRAIN OF THE SriDER MONKEY. 
23 
Kpi/cos, a ring ; elfios, shape. 
