IV. CLASS AVES, LinnS 



' Warmblooded, oviparous, Amniota, Allantoidea. Occipital 

 condyle single. Quadrate movable. Anterior extremities 

 transformed into wings. Covered with feathers. With inter- 

 tarsal joint. Not more than four toes, of which the first is 

 the hallux. Total number of recent species nearly 10,000, 

 of which about half are Oscines. 



1. Sub-CLASS AKCHAEOKNITHES (Carus), Gadow 



The three fingers and their metacarpals (I, II, III) remain 

 separate, each with a claw. Well developed remiges. Both 

 jaws with alveolar teeth. 



Amphicoelous. Caudal vertebrae more than thirteen, with- 

 out a pygostyle, but with paired rectrices. 

 Archaeopteryx. Oolite, Bavaria. 



2. Sub-CLASS NEOBNITHES, Gadow 



Metacarpals fused. Second finger the longest. 



Not more than thirteen caudal vertebrae. 



1. Division NEORNITHES EA TITAE, Merrem. Ter- 

 restrial, flightless. Without sternal keel. Quadrate with 

 single proximal knob. Without pygostyle. Coracoid and 

 scapula fused. No pterylae. Compound rhamphotheca. With 

 copulatory organ. 



A collective cosmopolitan group; with certainty since 

 the Miocene. 



? Diatryma. Eocene, New Mexico. 

 ? Gastornis, Dasornis. Eocene, Europe. 



