356 SYSTEMATIC ZOOLOGY. 



SUBCLASS II. ODONTORNITHES (Toothed Birds). 



These forms, which have been found only in American 

 rocks, are more like modern birds than is Archceopteryx, 

 but they differ from all existing birds in having teeth. 

 They had normal tails, and one form (Hesperornis, fig. 

 150) apparently was wingless, only a rudimentary humerus 

 persisting. Some of these toothed birds were about as 

 large as a pigeon; one was about three feet in height. 



SUBCLASS III. ORNITHUILE (Modern Birds). 



In all living birds teeth are lacking and the tail is re- 

 duced; and, excepting a few forms, all have well-developed 

 wings. The recent subdivisions of the subclass are based 

 upon characters not readily grasped by elementary stu- 

 dents, so we must content ourselves with a classification 

 founded on external features. The student should, how- 

 ever, remember that the so-called orders are in no wise 

 equivalent to orders in other groups of animals. 



ORDER I. STRUTHII (Ostriches). 



The ostrich-like birds have long running legs, and wings 

 so reduced as to be useless in flight, and with this the keel 

 of the sternum (p. 354) has disappeared. The foot con- 

 tains usually three, occasionally but two, toes. These 

 birds are mostly large, and embrace the true ostriches of 

 Africa, so valuable for their feathers; the South American 

 nandus, the feathers of which are used for feather dusters; 

 the emeus and cassowaries of Australia, and the nearly 

 wingless kiwi of Australia. 



