22 THE POPULAR SCIENCE MONTHLY. 



so that even those which have no thumbs on their hands, or have them 

 small and weak and parallel to the fingers, have always large and 

 well-formed thumbs on their feet. It was on account of this peculiar- 

 ity that the great French naturalist Cuvier named the whole group of 

 monkeys Quadrumana, or four-handed animals, because, besides the 

 two hands on their fore-limbs, they have also two hands in place of 

 feet on their hind-limbs. Modern naturalists have given up the use 

 of this term, because they say that the hind extremities of all monkeys 

 are really feet, only these feet are shaped like hands ; but this is a 

 point of anatomy, or rather of nomenclature, which we need not here 

 discuss. 



Let us, however, before going further, inquire into the purpose and 

 use of this peculiarity, and we shall then see that it is simply an 

 adaptation to the mode of life of the animals which possess it. Monk- 

 eys, as a rule, live in trees, and are especially abundant in the great 

 tropical forests. They feed chiefly upon fruits, and occasionally eat 

 insects and birds'-eggs, as well as young birds, all of which they find 

 in the trees ; and, as they have no occasion to come down to the 

 ground, they travel from tree to tree by jumping or swinging, and 

 thus pass the greater part of their lives entirely among the leafy 

 branches of lofty trees. For such a mode of existence, they require 

 to be able to move with perfect ease upon large or small branches, and 

 to climb up rapidly from one bough to another. As they use their 

 hands for gathering fruit and catching insects or birds, they require 

 some means of holding on with their feet, otherwise they would be 

 liable to continual falls, and they are able to do this by means of their 

 long finger-like toes and large opposable thumbs, which grasp a branch 

 almost as securely as a bird grasps its perch. The true hands, on the 

 contrary, are used chiefly to climb with, and to swing the whole 

 weight of the body from one branch or one tree to another, and for 

 this purpose the fingers are very long and strong, and in many species 

 they are further strengthened by being partially joined together, as if 

 the skin of our fingers grew together as far as the knuckles. This 

 shows that the separate action of the fingers, which is so important to 

 us, is little required by monkeys, whose hand is really an organ for 

 climbing and seizing food, while their foot is required to support them 

 firmly in any position on the branches of trees, and for this purpose 

 it has become modified into a large and powerful grasping hand. 



Another striking difference between monkeys and men is, that the 

 former never walk with ease in an erect posture, but always use their 

 arms in climbing or in walking on all-fours like most quadrupeds. 

 The monkeys that we see in the streets, dressed up and walking erect, 

 only do so after much drilling and teaching, just as dogs may be 

 taught to walk in the same way ; and the posture is almost as unnat- 

 ural to the one animal as it is to the other. The largest and most 

 man-like of the apes the gorilla, chimpanzee, and orang-outang also 



