EDENTATA. 141 



Bhadypus, Lin. 



The Sloths have cylindrical molars, and sharp canines longer than 

 those molars, two niammje on the breast, and fingers united by the skin, 

 and only marked externally by enormous compressed and crooked nails, 

 which, when at rest, are always bent towards the palm of the hand, or 

 the sole of the foot. The hind feet are obliquely articulated on the leg, 

 and rest only upon their outer edge; the phalanges of the toes are 

 articulated by a close ginglymus («.), and the first, at a certain age, 

 become soldered to the bones of the metacarpus or metatarsus, which 

 also, in time, for want of use, experience the same fate. To this incon- 

 venience in the organization of the extremities is added another, not less 

 great, in their proportions. The arm and fore-arm are much longer than 

 the thigh and leg, so that, when these animals walk, they are compelled to 

 drag themselves along on their elbows. The pelvis is so large, and their 

 thighs so much inclined to the sides, that they cannot approximate their 

 knees. Their gait is the necessary effect of such a disproportioned 

 structure.* They live on trees, and never remove from the one they are 

 on until they have stripped it of every leaf, so painful to them is the 

 requisite exertion to reach another. It is even asserted that to avoid the 

 trouble of a regular descent, they let themselves fall from a branch. The 

 female produces but a single young one at a birth, which she carries on 

 her back. 



The viscera of these animals are not less singular than the rest of 

 their conformation. The stomach is divided into four sacks, analogous 

 to the four stomachs of the Ruminantia, but without leaflets or other 

 internally salient parts, while the intestinal canal is short and without 

 a cfecum. 



M. Fr. Cuvier applies the name of Acheus to those species that have 

 three nails to the fore feet ; they have a very short tail. 



Bradypus tridactylus, L. ; Buff. XIII. v and vi. (The Ai)(6). A 

 species in which sluggishness and all the details of the organiza- 

 tion which produce it are carried to the highest degree. The thumb 



* M. Carlisle has observed that the arteries of the limbs commence by splitting 

 into an infinitude of ramifications, which afterwards unite in one trunk, from whicli 

 the usual branches proceed. This structure being met with in the Loris, whose gait 

 is almost equally sluggish, it is possible that it may exert some influence on this 

 slowness of motion. Independently of this, the Loris, the Ourang-Outang, the 

 Coaita, all very slow animals, are remarkable for the length of their arms. 



f^° (a) Ginglymus is a form of joint which resembles a hinge, and exists 

 amongst animals under two forms. In the first one of the bones has a pulley like 

 surface into which the other bone completing the joint is received. This is the 

 state of the knee and elbow joints in the human body, and it has received the name 

 of the angular ginglj'mus. The lateral or rotatory ginglymus is constituted by such 

 a union as admits of the convex end or process of one bone in a hallow of another. 

 — Eng. Ed. 



B^ (b) The name of Ai is given to the animal, because the plaintive sound 

 which it emits is exactly imitated by pronouncing the vowels a and i. In falling 

 from the branch, as is described above, this animal first rolls itself into a round ball ; 

 and, previously to its fall, it may be taken whilst it is attached to the branch, so 

 great is its apathy. — Eng. Ed. 



