CLASS AVES. 129 



ORDER STRUTHIONES (stroo thi 6'nez). 



The members of this order being strictly terrestrial, 

 lack several of the specializations characteristic of the 

 great majority of birds, those which fly. The bones, 

 with few exceptions, are unusually light ; while the 

 sternum, being unused as an attachment for muscles of 

 flight, is small and weak. The clavicles are rudimentary. 

 Though these birds, on account of their weight and the 

 shortness of their wings, are unable to fly, they are all 

 rapid runners. Their legs are long and powerful, being 

 capable of extraordinary muscular effort. When running, 

 they scarcely seem to touch the ground, and their speed 

 is materially increased by the flapping of their stout ru- 

 dimentary wings, which serve as balancers. 



The two members of the order treated, are the African 

 Ostrich and the South American Ostrich. Several other 

 members, which undoubtedly excelled them in size, are 

 now extinct. 



The African Ostrich is the largest living bird. There 

 is but one species, found in the interior of Africa, but 

 rarely in Asia, except in Arabia. Its head is naked, and 

 its short bill is somewhat broad and rounded at the 

 point. Its long tarsi are covered with scales, and its 



an ordinal system. Thus the form of the bill lias been made a basis of separat- 

 ing the almost interminable series of Passerine (//.< '*<> In) birds into C'onirostres 

 (ko nl roV trSz), with stout, conical bill; Denliroxtn* len ti rQs'trSz), with a toothed 

 and usually more or less hooked tip ; Tenitirostres (ten u i r5s' trez), with an elongated 

 and awl-shaped bill; and Fissirostres (f is el rSs'trez), with a depressed, wide gaped 

 bill. These distinctions have proved unreliable, and are generally discarded. In 

 such uncertainty, the classification here adopted is essentially that of Lilljeborg 

 (lilje'borg) in "A History of North American Birds," by Baird, Brewer, and 

 Ridgway. It is, however, considered only provisional. The sixteen orders given 

 in the table have been subdivided by recent authorities into several hundred 

 genera, and at least ten thousand species. The limits of this book will permit 

 the description of only a few species typical of each order, American examples 

 being generally chosen. 



