6/4 MANUAL OF ZOOLOGY. 



The most striking peculiarities, however, about the Sloths are 

 connected with their mode of life. The Sloths, in fact, are 

 constructed to pass their life suspended from the under surface 

 of the branches of the trees amongst which they live ; and for 

 this end their organisation is singularly adapted. The fore- 

 limbs are much longer than the hind-limbs, and the bones of the 

 fore-arm are unusually movable. All the feet, but especially 

 the fore-feet, are furnished with enormously long curved claws 

 (fig. 373), by the aid of which the animal is enabled to move 



Fig. 373. Hand of Three-toed Sloth {Bradypus tridactylus). (After Owen.) 



about freely, suspended back downwards from the branches. 

 Not only is this the ordinary mode of progression among the 

 Sloths, but even in sleep the animal retains this apparently 

 unnatural position. 



Owing to the disproportionate size of the fore-limbs, as com- 

 pared with the hind-limbs, and owing to the fact that the hind- 

 feet are so curved as to render it impossible to apply the sole 

 to the ground, the Sloth is an extremely awkward animal upon 

 the ground, and it has therefore recourse to terrestrial pro- 

 gression only when absolutely compelled to do so. Whilst the 

 name of " Sloth " may thus appear to be a merited one from 

 the point of view of a terrestrial Mammal, it is wholly unde- 

 served when the animal is looked upon as especially adapted 

 for an arboreal existence. In the Ai or Three-toed Sloth 

 (Bradypus tridactylus] there are three toes to each foot, and 

 these are short, completely rigid, and so enveloped in the in- 

 tegument as to leave nothing visible except the enormously 

 long and crooked claws. The hand and foot are jointed to 

 the arm and leg obliquely, so that the palm and sole cannot be 

 applied to the ground, but are turned inwards. The ungual 

 phalanges are also so articulated that the claws are bent in- 



