270 



GENERAL ZOOLOGY 



of both reptiles and birds, as judged by existing representa- 

 tives of those groups, it is classed witji the latter and is 

 looked upon as the most primitive known bird. Archseop- 

 teryx had feathers, and in this respect differed from all 

 reptiles, living or fossil. It is about as nearly a " missing 

 link" as science may reasonably expect to find when the 

 imperfection of the fossil record is considered, and its 



FIG. 102. Archceopteryx (A) and Hesperornis (B), two extinct toothed birds. 

 (After restorations by Knipe and Lucas.) 



structure is believed to indicate, with other evidence, that 

 birds were evolved from reptilian ancestors. 



SUBCLASS 2. NEORNITHES 



The birds in this group are characterized by having 

 several vertebrae at the tip of the tail fused to form a 

 " plowshare bone" which acts as a support for the large 

 tail feathers. The wing bones are reduced and more or 



