CHAPTER III 



PHYLOGENETIC (continued)— THE CLASSIFICATION OF BIRDS IN 

 BROAD OUTLINE— THE MAIN LINES OF THE EVOLUTION OF 

 THE CLASS AVES. 



Archornithes and Neornithes. The position of the Ostrich tribe in the 

 system. What the structure of the bony palate reveals. Paljeognathas and 

 Neognathae. The classification of the Palseognathae and of the Neognathas. 

 A hypothetical ancestor. The Grebes and Divers, Penguins and Petrels, Steg- 

 anopodous birds, the Accipitres, the Anseres, the Alectoromorphae, — the Game- 

 birds, Cranes and Rails, Plovers, Pigeons, the " Coraciiform " birds; the Passeres. 

 Numerical strength. 



ARCH^OPTERYX naturally forms the starting-point 

 in any comprehensive system of avian classification, 

 since it represents the lowest, because most reptilian, 

 of the whole Class Aves. Moreover, on account of its many 

 structural and peculiar characters, it is by common consent set 

 apart in a separate sub-class— Archornithes — as distinct from 

 the Neornithes, the sub-class which embraces all other known 

 forms. 



Though the Struthious or Ostrich-like birds are, by 

 modern systematists, regarded as the lowest, most primitive 

 of this Neornithine branch or sub-class, they are not, by many, 

 on this account looked upon as a natural group of birds ; that 

 is to say, as a group having a common origin. Rather it is 

 held they must be considered as descendants of several dis- 

 tinct stocks — four, or perhaps five isolated groups whose relation- 

 ship to the remainder of the birds is necessarily a matter for 

 conjecture rather than dogmatism. 



One of the strongest reasons among the older systematists 

 for regarding this assemblage as one bound by ties of affinity 

 was that all the members thereof had lost the power of flight, 

 and with it the characteristic median plate, or keel, which, in 

 flying birds, runs down the under surface of the sternum. 

 Hence they were placed together to form the " Order Ratitse " 



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