346 



SAUEOfSluA (BuiuS). 



Class AVES. 



I. Sub-class AROHiEOBNITHBS. 



Extinct birds of the Jurassic period. — Terrestrial and aerial. 1st, 2nd, 

 and 3rd metacarpals separate ; 2nd and 3rd fingers with three phalanges. 

 Conical teeth in upper jaw. Vertebrae amphicoelous. Caudal vertebrso 

 21, no ploughshare bone. Twenty-four tail-feathers (reotrices) attached 

 in pairs to 12 caudal vertebrae. 



1. Axchseopterygiformes. — Including the ArcJueapteryx from the 

 Bavarian Oolite. 



Fig. 181.— Types of Birds' Skclls. 



A, Skull of a gull (Larus), Sohizognathous type ; b, skull of raven, reduced (^gith- 

 ognathous): Pmx, premaxiilary ; Mx.p, maxillo - palatine ; Vo, vomer; PI, palatine; 

 Mx, maxilla ; Pt, pterygoid ; Q, quadrate. 



II. Sub-class Neornithes. 



Metacarpals fused with each other. Second finger longest ; third re- 

 duced. Caudal vertebrae apparently not more than 13 in number. 



