440 RASORES. PERDIX. 



lours to those of the back. Tail blackish-brown ; with 

 the shafts, tips, and bars, cream-yellow. Legs and 

 toes pale yellowish-brown. 



The female differs in not having any black or brown 

 on the neck and throat. Her breast is spotted with 

 blackish-brown ; and the general tints of her plumage 

 are paler. 



FAMILY IV. STRUTHIONID^l, FIG. 



THE passage from the preceding to the Struthionidae, the 

 fourth family of the order, is (as I have before observed, 

 when speaking of the present Order,) effected by certain 

 species of the Tetraonidce, where the bill acquires the de- 

 pressed form and shape of that of the American Rhea and 

 the Emeus of Australia, and where the feet, if not tridactyle, 

 exhibit at least great weakness and deficiency in the struc- 

 ture of the hind toe. In the present family, the typical 

 groups attain a height and bulk far surpassing the rest of 

 the feathered race ; but having wings so short and imperfect- 

 ly developed as to be totally unfit for the purposes of flight. 

 Their anatomy also exhibits a corresponding variation, the 

 os furcatorms being wanting, and the sternum itself desti- 

 tute of the keel, and presenting the appearance of a flat 

 plate, or buckler. Nearly allied to them, but possessing the 

 power of flight, ranks the genus Otis, by certain species of 

 which the immediate passage to the order Grallatores is ef- 

 fected. The birds of this family are inhabitants of the 

 plains, and frequently of sandy deserts, feeding upon herbs, 

 grain, and insects. They all run with great swiftness and 

 for a long continuance, and which appears to be their usual 

 mode of progress. Such of the family as are capable of 

 flight, when in this action, stretch out their legs behind 

 them. In disposition they are shy, savage, and stupid. 



