CONDITIONS OF MARSUPIAL STRUCTUEE. 207 



unguiculate one ? The answer need only be a reference 

 to Fig. 44; the requisite faculty of migration of the parent 

 with the tender offspring is gained by transferring the 

 locomotive power to the hinder pair of limbs extraordi- 

 narily developed, and aided by a correspondingly power- 

 ful tail; the fore-limbs being restricted in their develop- 

 ment to the size requisite for the marsupial offices and 

 other accessory uses. 



This is the condition or explanation of the seemingly 

 anomalous form and proportions of the kangaroo — so 

 strange, indeed, that the experienced naturalists. Banks 

 and Solander, may well be excused for surmising they 

 had seen a huge bird when they first caught a glimpse 

 of the kangaroo in the strange land which they, with 

 Cook, discovered. 



The rapid course of the kangaroo is by a succession of 

 leaps, in which twenty to thirty yards are cleared at a 

 bound ; the herbivore, instead of a swift courser on four 

 pretty equally developed hoofed extremities, is, in Aus- 

 tralia, a leaping animal ; and the saltatorial modification 

 'of the mammalian skeleton is here shown in that of one 

 of the swiftest and most agile of the numerous species of 

 kangaroo, the Macropus elegans. 



In this kangaroo, 13 vertebrse are dorsal, 6 are lumbar, 

 2 are sacral, and 28 are caudal, the first fourteen of which 

 have haemapophyses. These elements coalesce at their 

 distal ends, and form small haemal arches ; they overspan 

 and protect from pressure the great bloodvessels of the 

 tail, the powerful muscular fasciculi of which derive in- 

 creased surface of attachment from these hsBmal arches. 

 The pelvis is long; the strong prismatic ilia, 52, and the 

 ischia, 63,- carry out the great flexors and extensors of the 

 thigh to a distance from their point of insertion — the 



