522 



BIRDS. 



Some Contrasts between modern Ratiia and modern Carinatee. 



Ratit^. 



Carinat^. 



Running-Birds, with wings more or less 

 degenerate and unused in flight, with 

 a keelless raft -like breast-bone. 



The skull is dromaeogfnathous, the pala- 

 tines not articulating with the basi- 

 sphenoidal rostrum. 



The sutures in the skull remain for a long 

 time distinct. 



The long axes of the adjacent portions of 

 the scapula and coracoid lie almost in 

 the same line, or form a very obtuse 

 angle. 



The clavicles are small or absent. 



The ilium and ischium are not united 

 behind. 



The feathers of the adult have free barbs. 



Flying-Birds, with wings almost always 

 well exercised in flight, with a keeled 

 breast-bone. 



(The keel is rudimentary in the New 

 Zealand parrot Stringops^ in the ex- 

 terminated Dodo {Didus)j and in the 

 extinct Aptomis — one of the rails. 

 The penguins do not fly at all, the 

 Tinamou, the Hoatzin, and some 

 • other birds, fly very little.) 



Except in the Tinamous, the skull is never 

 dromseognathous, the palatines arti- 

 culating with the basisphenoidal ros- 

 trum. 



The sutures in the skull almost always 

 disappear very early. 



The scapula and coracoid meet at a sharp 

 angle. 



The clavicles are in most cases very well 

 developed. 



The ilium and ischium unite, enclosing a 

 sciatic foramen. 



The barbs of the feathers are generally 

 united. 



Pedigree of Birds. 



Birds have many structural affinities with Reptiles, the 

 ancient Dinosaurs present approximations to Birds, the 

 extinct flying Pterodactyls show that it was possible for 

 flight to be developed among Reptiles, the oldest bird— 

 Archmopteryx — is in many ways a connecting-link between 

 the two classes, and the development of some Birds reveals 

 many remarkable resemblances with that of Reptiles,— 

 therefore, with the strength of the general argument for 

 evolution to corroborate us, we are safe in concluding that 

 Birds evolved from a Reptile stock. 



As we have already emphasised the common characters 

 which unite Birds and Reptiles in the alliance Sauropsida, 

 and have noticed the importance of Dinosaurs and of 



