of the Sloths to their peculiar Mode of Life. | 23 
of a branch, and their heads reclining on their own bosom. The animal is 
thus rolled up nearly to the form of a ball; the entire vertical column, in- 
cluding the neck, assumes a nearly circular curve; and not only is the weight 
of the whole body maintained in an attitude of ease and safety, but the head 
is supported between the arms and chest, and the face lies buried deep in the 
long wool which covers these parts, and is thus protected during sleep from 
the myriads of insects that would otherwise attack it, 
The teeth of the Sloth also present peculiarities which are in harmony with 
the other characters of the animal; there are no incisors, because the leaves 
are brought to the mouth, being collected from the branches by the powerful 
claws which terminate the hand and perform the office of incisors. Besides 
the four canine teeth, there are on each side four molars in the upper and three 
in the lower jaw. The construction of these teeth is the most simple that exists; 
they are composed of a cylinder of bone, encased with enamel, and hollow at 
the two extremities; the upper cavity being produced by the act of masti- 
cation, which wears away the softer bony substance of the interior more 
readily than the exterior enamel, and the lower cavity being filled with gela- 
tinous pulp, which maintains the continual growth of the tooth ; these simple 
teeth being employed exclusively in the mastication of buds and leaves, are 
fully adequate to the wants of an animal which has no need of the more com- 
plicated compound tooth of quadrupeds that feed on the ground, and masticate 
vegetables of a harder or more miscellaneous kind. 
Should the above criticisms be correct, which I have presumed to make on 
almost the only passage in the works of Cuvier that I do not read with entire 
assent and admiration, the construction of the Sloth is not only relieved from 
the imputation of feebleness or imperfection, and still more from the charge of 
monstrosity ; but adds another striking case to the endless instances of perfect 
mechanism and contrivanee which we find pervading every organ of every 
creature, when viewed in relation to the office it is destined to fulfil; and 
affords a new exemplification of the principle, which has been so admirably 
illustrated by the judicious Paley, * that the animal is fitted to its state." 
The views we have been taking of the anatomy and economy of the Sloth 
are abundantly confirmed by the observations on the habits of this animal, 
published by Mr. Waterton in his Wanderings in South America. “ This sin- 
