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OSTRICH.— Struthlo amielus. 



CURSORES, OR RUNNING BIRDS. 



ITH the Ostrich commences a most important group of birds, containing the 

 largest and most powerful members of the feathered tribe, and termed Cursores, 

 or Running-Birds, on account of their great speed of foot and total impotence of 

 wing. All the birds belonging to this order have the legs developed to an extra- 

 ordinary degree, the bones" being long, stout, and nearly as solid as those of a 

 horse, and almost devoid of the air-cells which give such lightness to the 

 bones' of most birds. Bv the aid of the microscope, the peculiar character of the 

 bone is clearly shown, though the bone of an Ostrich or Cassowary is very different from the 

 same bone in a fowl or a pigeon. The wings are almost wanting externally, their bones, 

 although retaining the same number and form as in ordinary birds, being very small, as if sud- 

 denly checked in their growth. The huge wing muscles which give such prominence to the 

 breast of flying birds, are therefore not required, and the breast-bone is consequently devoid of 

 the projecting keel, and is quite smooth and rounded. 



