CURSORE5; AND RASORES. 485 



retain their marrow, and the sternum (fig. 189, B) is destitute 

 of the prominent ridge or keel, to which the great pectoral 

 muscles are attached (hence the name of Ratidtz, applied by 

 Huxley to the order). In the Ostrich, the pubic bones of the 

 pelvis unite to form a symphysis pubis, as they do in no other 

 bird ; and in all, the pelvic arch possesses unusual strength and 

 stability. The legs are extremely robust and poweiful, and the 

 hind-toe is entirely wanting, except in the Aj>teryx, in which it 

 is rudimentary. The anterior toes are two or three in number, 

 and are provided with strong blunt claws or nails. The plumage 

 presents the remarkable peculiarity that the barbs of the 

 feathers, instead of being connected to one another by hooked 

 barbules, as is usually the case, are remote and disconnected 

 from one another, presenting some resemblance to hairs 



Fig. i8g. — Cursores. A, Foot of the Ostrich {Jtniikia camelus); B, Sternum of 

 the Emeu {Drojttaius Nova-Iiollandia). 



The order Cursores may be divided into the two families of 

 the StruthionidcB and the ApterygidcB — the former characterised 

 by the absence of the hallux, and comprising the Ostrich, 

 Rhea, Emeu, and Cassowary, with several extinct forms ; the 

 latter comprising only the Apteryx of New Zealand, and char- 

 acterised by the possession of a rudimentary hallux. 



The African Ostrich {Struthio catnelus) occurs in the desert 

 plains of Africa and Arabia, and is the largest of all living 

 birds, attaining a height of from six to eight feet The head 

 and neck are nearly naked, and the quill-feathers of the wings 

 and tail have their barbs wholly disconnected, constituting the 

 ostrich-plumes of commerce. The legs are extremely strong, 

 and are terminated by two toes only (fig. 1S9, A), these cori- 

 sisting respectively of four and five phalanges, showing that it 

 is the hallux and "the innermost toe which are wanting. ■ The 

 internal one of the two toes is much the largest, and is clawed, 

 the outer toe is small and clawless. The Ostriches run with' 

 extraordinary speed, and can outstrip the fastest horse. They ' 



