30 A BOOK OF BIRDS 



As in the case of the species already mentioned, the males under- 

 take the duties of incubation and the care of the chicks. Several 

 hens combine and lay their eggs together in one nest, so that the male 

 at last is left to brood about twenty eggs. These are of a cream 

 colour, and deeply pitted ; thereby they stand in sharp contrast with 

 the eggs of the Emeu and Cassowary, which are of a beautiful green 

 colour. 



There are three species of Rhea, the smallest being Darwin's 

 Rhea, distinguished besides by the fact that the legs are feathered 

 much farther down than in the two remaining species. 



The African Ostrich (Plate I. fig. i) is the giant among living 

 birds, the male standing some eight feet high. In that he exceeds 

 the female in size, he differs from the other ostriches so far described, 

 wherein the females are the larger. Furthermore, the African 

 Ostrich differs from all his relatives in that he is conspicuously different 

 from his mate in coloration, having the body clothed in a livery of 

 glossy black, relieved by the pure white of the wing- and tail-feathers, 

 which are the feathers so highly prized for millinery purposes. The 

 head and neck are almost bare of feathers, while the massive legs 

 are absolutely naked. 



In the possession of a tail, the African Ostrich is also peculiar 

 among the Ostrich tribe. 



As in the Rhea, the wings are of relatively large size, and, though 

 useless for flight, they largely aid him when running, being made 

 to serve as sails. The plumage of the female is of a very sober brown 

 hue. 



The Ostrich stands alone among birds in the structure of the foot, 

 which has the toes reduced to two in number, and of these one is 

 so small as to play but a slight part in supporting the body. 



The African Ostrich differs from its relatives in that both sexes 

 share the work of incubation ; and here the difference in plumage 

 plays an important part. The female, with her dull, sandy-coloured 

 dress, sits by day, so that she is practically invisible when seen against 

 the arid waste chosen for the nesting-site. The male sits by night, 

 when his dark plumage renders him invisible also. Like the Rhea, 

 the Ostrich is polygamous, and several hens lay their eggs together 

 in the same nest. Though four distinct species of Ostrich are 



