524 STEUTHIONID^ STRUTHIO 



in a membranous groove near the middle of the bill ; wings short 

 and imperfect with long soft plumes ; tail moderate, of curved 

 pendant plume-like feathers ; tarsi very long and strong, covered in 

 front on the lower half with transverse scutes ; toes only two in 

 number, the third and fourth, short and robust, the outer the 

 shorter ; claws short, broad and flattened. 



Four species of Ostriches are now generally recognised, but the 

 differences are not very marked or clearly defined. In addition to 

 the Southern Ostrich (S. australis) and the original North African 

 and Arabian bird (S. camelus), the Somali (S. molybdophanes) and 

 East African {S. masaicus) Ostriches have recently been recognised 

 as distinct. 



Pig. 161. — Head of Struthio australis, after Wolf. 



The males of the North African and Masai Ostriches have 

 reddish necks, which in the former is very thinly, in the latter 

 very thickly clothed with woolly down ; the males of the Somali 

 and Southern Ostrich have bluish-grey necks, while the former 

 is distinguished from the latter by the presence of a horny shield 

 at the top of the head surrounded by downy hairs. This is entirely 

 absent in the South African bird. 



The eggs of the various species of Ostriches show differences 

 which seem to be fairly constant. Those of S. camelus are quite 

 smooth and polished with no pores or pits such as are characteristic 

 of the other three species. In S. masaicus and S. molybdophanes 

 the pits or pores are of a deep purple colour, while those of S. 

 australis are but slightly darker than the rest of the surface of the 

 shell. 



