and they perform their climbings and other motions 

 in the trees, by leaping and by grasping jointly. 

 Their tails, which in some of the species are very 

 long, assist in steadying their bodies, both when they 

 leap and when they walk, which they do upon all 

 fours, and though with a leaping and shambling 

 motion, yet a good deal more steadily than the qua- 

 drumana that have no tails. That their superior 

 powers of locomotion on the ground correspond 

 with the peculiarity of their organisation, is proved 

 both by the observation of them in a state of confine- 

 ment, and by the fact of their assembling in troops, 

 and marching considerable distances, in order to 

 plunder in the plantations of the people in the coun- 

 tries which they inhabit thickly. 



When we turn our attention to the quadrumana of 

 the American continent, we find considerable differ- 

 ences in their organs of climbing, and these are 

 accompanied by certain differences in the number of 

 the teeth. The most remarkable difference in their 

 climbing organs, which however is not common to 

 the whole, is the addition of a fifth one, which is 

 equally efficient with the other four, if indeed it is 

 not more so. This is a prehensile tail, or a tail capable 

 of laying hold by curling once or oftener round the 

 branch or other substance by which the animal wishes 

 to support itself; and if we except the kangaroo, 

 whose tail assists as a third foot and as a weapon of 

 defence, there is not, in the whole of the mammalia, 

 a tail of anything like the efficiency of that possessed 

 by those American quadrumana. In some of the 

 species it is longer than the whole body, and yet the 

 bodies are of a very lengthened form in proportion to 

 the size or weight. A considerable portion of the 

 tail toward the extremity is covered with naked skin 

 on the under side, very similar to that with which 

 the prehensile paws have the palms and undersides 

 of the fingers covered. The animals which are fur- 

 nished wilh this appendage, have all the limbs exceed- 

 ingly long, the joints with very loose and varied 

 motions, and the whole frame supple, so that it readily 

 bends in any direction. The hands, or climbing paws, 

 are less perfectly formed than those of the apes 

 which have no prehensile tail, and especially those 

 which have no tail at all, but which depend entirely 

 on the feet both for the extent and the direction of 

 their motions. On the ground they are very helpless 

 animals, and they are more helpless in appearance 

 than they are in reality. But the rapidity with which 

 they can ascend a tree, and the distance to which 

 they can swing themselves from one tree to another, 

 are both much greater than one would suppose, from 

 the apparent feebleness of the animals upon the 

 ground. It signifies little in what direction the motion 

 is taken, or which end of the animal is made the 

 point of rest, and which is ready to seize the new 

 support. They can catch hold with the tail, swing 

 till they have got the requisite momentum, and then 

 project themselves till they can lay hold of a branch, 

 and if the next branch is at a distance, they can swing 

 again upon the fore leg, and project themselves so as 

 to lay hold with the tail. In this way they tumble 

 about with astonishing rapidity, and apparently often 

 for mere sport. There are many species of them, 

 differing a little from each other in many particulars, 

 but all agreeing in the use of this prehensile instru- 

 ment. Under the article ATELES will be found 

 figures and descriptions of two of the most remark- 

 able of the long-legged species, and we shall here 



MAMMALIA. 147 



present a figure of another, of which the limbs are 

 not so long, but the tail is perhaps longer in propor- 



tion ; and in order to convey some idea of the action 

 of these animals we have represented it in the action 

 of swinging by the tail. 



This species, and several others of the section 

 to which it belongs, are remarkable for the loud and 

 disagreeable sound of their voices. The bone of the 

 tongue in many of the quadrumana is far more pro- 

 duced than in the human subject ; and it is furnished 

 with a large cavity or sac, by means of which, as it 

 is understood, these creatures are enabled to produce 

 that loud and dismal voice from which they obtain 

 the popular name of howlers. In them there are five 

 fingers on all the paws, but the thumbs even of the 

 anterior extremities have very little freedom of mo- 

 tion, so that their principal mode of grasping is with 

 the paw itself like a hook. Others again, the very long- 

 legged ones to which we have alluded above, have the 

 thumbs of the fore paws concealed under the skin, and 

 incapable of any kind of action against the finger?. 



To these succeed others which have the tails Ion?, 

 but not prehensile, and the fingers furnished with 

 crooked claws, instead of flat nails like those possessed 

 by the more characteristic hand climbers. These 

 last approach the squirrels in their style of motion 

 among the branches, holding on partly by the grasp 

 of the fingers and partly by the points of the claws, 

 while the tail, which is covered with soft and rather 

 long hair for the whole of its length, and which though 

 not prehensile is very muscular, is understood to eerve 

 as a parachute, which is the purpose of the produced 

 tails of all the climbing animals which have not per- 

 fect grasping paws, or extensile skin, to assist them in 

 their motions from branch to branch. 



It would, however, be impossible to notice in a 

 general sketch of the mammalia all the varieties of 

 the hand or grasping paw at the extremity of the leg 

 as a climbing organ. In proportion as the food of 

 the animals ceases to be wholly or chiefly of a vege- 

 table nature, the paws begin to assume a compound 

 character, retaining still the power of grasping, and 

 often having 1 a thumb free in its articulation, but not 

 acting directly against the fingers, sometimes having 

 a mere tubercle against which the fingers act when 

 K2 



