66 4 



BIRDS. 



The old classification of birds into snatchers, perchers, climbers, 

 scratchers, stilt-walkers, and swimmers was interesting and suggestive, 

 but an arrangement of this sort is bound to be misleading, since birds 

 of very different structure may have very similar habits. 



It may be of interest to contrast the two divisions of living birds, but 

 the distinctions are not all equally well grounded, and to most of them 

 there are exceptions. 



SOME CONTRASTS BETWEEN MODERN RATIT/E AND 



MODERN CARINAT^. 



CARINAT.*:. 



Running Birds, with wings more 

 or less degenerate and unused in 

 flight, with a keelless raft-like breast- 

 bone. 



The skull is clromaeognathous, 

 i.e. the vomer is interposed between 

 the palatines, the pterygoids, and 

 the basisphenoidal rostrum. 



The sutures in the skull remain 

 for a long time distinct. The 

 quadrate articulates with the skull 

 by a single head. 



The long axes of the adjacent 

 portions of the scapula and coracoid 

 lie almost in the same line, or form 

 a very obtuse angle, and the two 

 bones are fused. 



The clavicles are small or absent. 



The ilium and ischium are not 

 united behind, except in old Rheas 

 and Emus. No pygostyle. 



The feathers of the adult have 

 free barbs. There is no oil gland, 

 except in the kiwi. There are no 

 regularly arranged pterylae. 



The male has a penis. 



The young are always praecoces. 



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 exterminated Dodo (Did us], 

 and in the extinct Aptornis 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 dromaeognathous, 

 i.e. the vomer is not fused with 

 the neighbouring bones of the 

 palate, and the palatines articulate 

 with the basi-sphenoidal rostrum. 



The sutures in the skull almost 

 always disappear very early. The 

 quadrate articulates by a double 

 head. 



The scapula and coracoid meet 

 almost at right angles, and are 

 separate from one another. 



The clavicles are in most cases 

 very well developed. 



The ilium and ischium unite, 

 enclosing a sciatic foramen. Usually 

 a pygostyle. 



The barbs of the feathers are 

 generally united. There is usually 

 an oil gland. 



The male has rarely a penis. 

 The young may be praecoces or 

 altrices. 



