BIEDS. 



PEOFESSOK HUXLEY {Proc. Zoo. Soc, 1867) showed, by the near approach 

 of members of the class AvES to Ebptilia in all essential and fimdamental 

 points of structure, that the phrase " Birds are greUtly modified Keptiles " would 

 hardly be an exaggerated expression. After having detailed fourteen principal 

 points in which Aves and Reptilia agree with one another and differ from 

 Mammalia, he concluded that the class Aves, while well enough defined from 

 all existing Reptiles, is nevertheless far more closely connected with the class 

 Eeptilia than with any other. 



Classification. He divides Birds into groups : — 

 i. Where the tail itself (not the quill feathers it supports) is longer than the 



body SAUEtTRB. 



ii. Where the tail is shorter than the body — Ratit^ and Carinat^. 



The first group (i.), the SADRtrB.si (lizard-tailed birds), is represented by the 

 solitary fossil remains of Archceopteryx lithograpJiica. These fossil remains, only 

 discovered in 1861 by Andreas Wagner in the Upper Oolites of Solenhofen, in 

 Bavaria, indicate that creatures existed in the Upper Jurassic geological age, 

 which were undoubtedly birds in their general structure, although very different 

 from those now existing. They were about the size of a Rook, and clothed with 

 feathers, but the jaws were armed with teeth ; three of the digits of the fore 

 limb were free and furnished with claws, and the tail consisted of a series of 

 elongated vertebras gradually tapering to the extremity, each vertebra bearing a 

 pair of well-developed feathers. As the skeleton of the tail rather resembled 

 that of a reptile than that of a modern bird, the name SAtTRURiE, signifying 

 " lizard tailed," has been applied to the group. 



The second group (ii.), where the tail is shorter than the body, is itself divided 

 into the Ratitce (ii.), those birds having the sternum or breast-bone without a keel, 

 and the Carinatce (iii.), having the breast-bone with a keel (see pp. 6-8). 



(ii.) Eatit^. 

 (Breast-bone without a keel.) 

 These constitute a group, very distinct in many important characters from aU 

 other known birds. They derive their name from the sternum or breast-bone 

 having no keel, and therefore resembling a raft or flat-bottomed boat (ratis). 

 Their wings are so greatly reduced in size and strength that they do not possess 

 the power of flight so characteristic of the majority of birds. The feathers are 

 always soft and loose, the barbs being " disconnected," or not united together by 

 minute hooks, as in most other birds, and there is no marked distinction between 

 feathered and unfeathered tracts upon the skin. The oil gland is absent. 



In addition, the Ratitce (like the Tinamous) have the upper mandible covered 

 B 



