CLASS II. AVES: ORDEE 6. CUR80RES. 
259 
OSTEICHES^ 
ORDER 6. CURSORES. 
Of the Cursores or Bunners, ■whicli have been inchided by many authors among the Gralhi- 
tores, the Common Ostrich is a prominent example. They are nearly all large birds, with strong 
and generally elongated legs ; the wings, on the contrary, are always reduced to a rudimentary 
condition, although the bones in number and form agree with those of the wings of other birds. 
In consequence of this small size of the wings, these birds are quite incapable of flight, and the 
only use they ever appear to mate of them is to spread them out as if to catch the air, and thus 
aid them in running. In accordance with this deficiency of the power of flight, the bones are 
almost entirely destitute of the air-cells which in the ordinary birds give so much lightness to the 
