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XIII. CURSORED RUNNERS. 



Though all the birds which belong to the Grallatorial 

 series, the Storks and Herons excepted, are remarkable for 

 their peculiar adaptation for speed of foot, those which seem 

 to me to constitute the present order are pre-eminent in this 

 respect. Three natural groups or families, easily distinguish- 

 able, insomuch that their natural affinity is not very readily 

 perceived, agree in possessing this character, however much 

 they may differ in other circumstances, especially with respect 

 to flight. 



The most remarkable of these families, that of the Stru- 

 ihioninoB or Ostriches, in some respects allied to the Rasorial 

 families, is composed of very large birds, having the neck 

 and feet elongated, the bill short, the tibia bare below, the 

 tarsus very strong, the toes short and stout, the hind toe 

 always, and in one species the second toe, wanting. The 

 African Ostrich, Struthio Camelus; the Indian Cassowary, 

 Casuarius Emu ; the American Nandu, Rhea Americana ; 

 Darwin's Nandu, Rhea Darwinii; the Emeu of New Hol- 

 land, Dromiceius Novse-Hollandiae, are all the species known 

 of this family, singular chiefly on account of the merely rudi- 

 mentary state of the wings, and the corresponding modifi- 

 cations in the formation of the sternum and clavicles. Being 

 thus incapable of flying, these birds might perhaps constitute 

 an order by themselves ; but in that case the Penguins, which 

 yet to many seem not entitled to such distinction, ought to 

 be separated from the diving sea-birds. However, as none 



