PROGRESSIVE MOTION IN QUADRUPEDS. 441 



obliging it to move forwards only by a succession 

 of leaps. The hare may be said, indeed, to walk 

 with its fore legs only, while it hops or gallops w ith 

 the hinder ; but this disadvantage is amply com- 

 pensated by its amazing swiftness when running at 

 full speed. 



Animals like the hare, in which, from the great 

 length of the hinder limbs, the posterior half of the 

 body is higher than the anterior, run much better 

 up an acclivity than on level ground. In a descent, 

 on the contrary, they are obliged to pursue an 

 oblique and zig-zag course, otherwise they would 

 be in danger of oversetting, as happens occasionally 

 to the Agouti and the Guitiea pig, when these 

 animals attempt to run down hill. 



The Sloth, which is formed for clinging with 

 great tenacity to the boughs of trees, presents a 

 remarkable contrast to the animals we have just 

 noticed ; its fore legs being much longer than the 

 hinder, and its movements being proverbially slow. 

 The peculiar modifications of its muscular powers 

 are probably consequences of the singular mode in 

 which, as I shall afterwards have occasion to notice, 

 its arteries are distributed. 



The Camelopard, likewise, has the fore legs much 

 longer than the hinder. The object of this con- 

 formation was probably to elevate the anterior part 

 of the spine, so as to raise the head as much as 

 possible; and also to give a considerable inclination 

 to the whole column, for the purpose of distributing 

 more equally the weight of the head and of the 

 very long neck upon all the legs ; for the length of 

 the neck is fully equal to that of the trunk. It is 

 evident that if the body had been placed in the 



