4G 



ANIMAL LOCOMOTION. 



Scrapers ; the Columhm, or Doves ] the Fasseres ; and the 

 Raptor es, or Birds of Prey. 



The first five orders have been classified according to their 

 habits and modes of progression. The Natatores I shall con- 

 sider when I come to speak of swimming as a form of locomo - 

 tion, and as there is nothing in the movements of the wading, 

 scraping, and climbing birds,^ or in the Passeres ^ or Raptor es, 

 requiring special notice, I shall proceed at once to a considera- 

 tion of the Cursor es^ the best examples of which are the 

 ostrich, emu, cassowary, and apteryx. 



The ostrich is remarkable for the great length and develop- 

 ment of its legs as compared with its wings (fig. 24). In this 

 respect it is among birds w^hat the kangaroo is among mammals. 

 The ostrich attains an altitude of from six to eight feet, and 

 is the largest living bird known. Its great height is due to 

 its attenuated neck and legs. The latter are very powerful 

 structures, and greatly resemble in their general conformation 

 the posterior extremities of a thoroughbred horse or one of the 

 larger deer — compare with fig. 4, p. 21. They are expressly 

 made for speed. Thus the bones of the leg and foot are in- 

 clined very obliquely towards each other, the femur being in- 

 clined very obliquely to the ilium. As a consequence the 

 angles made by the several bones of the legs are compara- 

 tively small ; smaller in fact than in either the horse or deer. 



The feet of the ostrich, like those of the horse and deer, 

 are reduced to a minimum as regards size ; so that they 

 occasion very little friction in the act of walking and running. 

 The foot is composed of two jointed toes,^ which spread out 

 when the weight of the body comes upon them, in such a 

 manner as enables the bird to seize and let go the ground 

 with equal facility. The advantage of such an arrangement 

 in rapid locomotion cannot be over-estimated. The elasticity 

 and flexibility of the foot contribute greatly to the rapidity 



1 The woodpeckers climb by the aid of the stiff feathers of their tails ; the 

 legs and tail forniing a firm basis of support. 



2 In this order there are certain birds — the sparrows and thrushes, for 

 example— which advance by a series of vigorous leaps ; the leaps b"i ng of au 

 intermitting character. 



3 The toes in the emu amount to three. 



