HAND OP MAMMALS. 333 



provided with four grasping hands, and frequently also with a pre- 

 hensile tail, did not require this accessory aid flat nails sufficed 

 to give the soft finger-ends the solid support they needed ; and 

 it is only in the American squirrel-monkeys, where the fore- 

 feet are not hands (as in the other monkeys) but mere paws, that 

 the fingers are armed with claws. In the dog, the hare, and 

 several other animals, where the claws are used neither for 



Hand of the Sloth. 



burrowing nor climbing, nor for defensive or offensive war- 

 fare, they afford the advantage of giving the feet a greater 

 steadiness while running ; and in the jerboa, which required a 

 particular contrivance to be able safely to execute its enormous 

 leap, we find, besides the strong claw with which the three toes 

 of the hind-feet are provided, a very small spur or back-toe 

 with its corresponding claw, which naturally breaks the impetus 

 of the fall. 



The cloven condition of the hoof in the cervine and bovine 

 races is evidently designed to impart lightness and elasticity to 

 the spring ; and in order to give full effect to such an arrange- 

 ment, many species are provided with a special glandular seba- 

 ceous follicle between the toes, whose office is to furnish a 

 lubricating secretion, calculated to prevent injury from friction 

 of the digits one against the other. In the stag and antelope 

 the hoofs are compact and vertical, to heighten the firmness of 

 the spring when bounding through weedy thickets and on 

 grassy moors ; but in the reindeer the joints of the tarsal bone 

 admit of lateral expansion, and the front hoofs curve upwards, 

 while the two secondary ones behind (which are but slightly 

 developed in the fallow-deer and others of the same family) are 



