ORDER CURSORES ; GENERAL CHARACTERS. 485 



absence of wings, bnt in the character of the plumage, that the 

 want of adaptation of these Birds to flight in the air is mani- 

 fested. For, as already stated ( 325), the barbs of the feathers 

 have so little adhesion to each other, that the air can pass readily 

 between them ; and in some species they are at such a distance 

 from each other, as to give the whole feather the appearance of 

 a stout branching hair. All these Birds construct their nests 

 upon the ground ; and in several species it appears that nume- 

 rous females lay in the same nest ; the eggs, to the number of 

 thirty, or even more, being chiefly sat on by the male. 



437. As in most other very aberrant groups, the number of 

 species contained in this order is small; but they differ widely from 

 each other in form and structure ; so that they might be almost 

 regarded as types of distinct families. The beak, in particular, 

 presents singular varieties in shape ; and there is also a varia- 

 tion in the number of toes. The Cursores, with the beak 

 depressed (that is, flattened horizontally) have the longest and 

 strongest legs, and run with remarkable velocity: this group 

 includes the Ostrich^ properly so called, which has only two 

 toes; and the Rhea, or American Ostrich, the Cassowary, and the 

 Emeu, which have three toes, all turned forwards. Of the 

 Cursores with a compressed (or vertically-flattened) beak, only a 

 single genus is known, and this is now extinct, the Dodo ; this 

 had four toes, one of them directed backwards. And lastly, we 

 find in the Apteryx a prolonged form of beak, resembling that 

 of the Tenuirostres, with four toes, of which the posterior one 

 is scarcely developed. Each of these species will be briefly 

 noticed. 



438. In the Ostrich the wings are sufficiently developed to 

 accelerate the speed of the Bird, when running along the plains 

 it frequents ; although the plumage is lax and flexible. The 

 African Ostrich, which has been known from remote antiquity, 

 is the tallest of all Birds at present known to exist ; it attains 

 the height of six feet and a half, or even eight feet ; and is 

 chiefly distinguished by the presence of only two toes upon each 

 foot, one of them being much larger than the other (Fig. 185). 

 It inhabits the sandy deserts of Arabia and Africa, everywhere 



