ANIMAL LOCOMOTION 189 



out to the fullest extent, and then leaving go of 

 their support and taking a fresh hold when they 

 reach another branch. During their progress the 

 animals usually employ first the one hand and then 

 the other in the manner of a gymnast practising 

 on the hanging rings, but occasionally they will 

 grasp a bough with both hands, and with a mighty 

 effort hurl themselves forward through the air 

 and alight upon another tree further away. Gib- 

 bons have been known to cover a distance of forty 

 feet in a single flying leap. 



The Canadian jumping-mice and the jerboas 

 are also able to walk upon their hind legs, but 

 when travelling fast they progress in a series of 

 jumps. The former animal, which attains to a 

 length of about three inches from the tip of its 

 snout to the root of its tail, is reported to be more 

 agile than any other rodent, and when progressing 

 at full speed it can take a leap measuring as much 

 as ten feet in length. It exhibits great ability in 

 dodging and doubling when endeavouring to elude 

 the pursuit of a foe. 



The jerboas, all of which are characterised by 

 the great development of their hind legs, are divided 

 into several distinct groups, which differ the one 

 from the other according to the number of toes 

 upon the hind feet. One of the largest species is 

 the Kirghiz jerboa, of Central Asia, which measures 

 about seven inches in length, exclusive of its long 

 tail, and is so fleet of foot that a man on horseback 

 cannot overtake the creature in chase. 



The kangaroos and the Cape jumping-hare are 



