THE MODES OF PROGRESSION. 156 



but with this difference, that the body always rests on two legs 

 at least. The limbs are raised in a determinate order, usually 

 in such a manner that the hind-leg of one side succeeds the 

 fore-leg of the opposite side. Some animals, as the giraffe, the 

 lama, and the bear, raise both legs of one side at the same mo- 

 ment. This is called ambling or pacing. 



296. RuNjSTisrG consists of the same successions of motion 

 as walking, so accelerated that there is a moment between two 

 steps when none of the limbs touch the ground ; in the horse 

 and dog, and in most mammals, a distinction is made between 

 the walk, the trot, the canter, and the gallop, all of which have 

 different positions or measures. The trot has but two measures. 

 The animal raises a leg on each side, in a cross direction ; that 

 is, the right fore leg with the left hind leg, and so on. 

 The canter has three measures. After advancing the two fore 

 legs, one after the other, the animal raises and brings forward 

 the two hind legs, simultaneously. When this movement is 

 greatly urged, there are but two measures ; the fore legs are 

 raised together, as well as the hind legs, it is then termed a 

 gallop. 



297. LEAPING consists in a bending of all the limbs, fol- 

 lowed by a sudden extension of them, which throws the body 

 forwards with so much force as to raise it from the ground, 

 for an instant, to strike it again at a certain distance in ad- 

 vance. For this purpose, the animal always crouches before 

 leaping. Most animals make only an occasional use of this 

 mode of progression, when some obstacle is to be surmounted ; 

 but in a few instances, this is the habitual mode. As the hind 

 legs are especially used in leaping, we observe that ah 1 leaping 

 animals have the posterior members very much more robust 

 than the anterior ; as frogs, kangaroos, jerboas, and hares. 

 Leaping is also common among certain birds, especiaUy among 

 sparrows, thrushes, &c. Finally, there is also a large number 

 of leaping insects, such as fleas, grasshoppers and crickets, in 

 which we find the posterior pair of legs much more developed 

 than the others. 



298. CLIMBIKG is merely walking upon an inclined or 

 upright surface. It is usually accompli shed by means of sharp 

 nails ; and hence many carnivorous animals climb with great 

 facility, such as the cat tribe, lizards, &c., many birds, the 

 woodpeckers and parrots, &c., have the toes arranged in two 



