10 



STRUCTURE AND CLASSIFICATION OF BIRDS 



So much then for the arrangement of the feathers in the 

 typical bird selected ; we must now consider the divergencies 

 from this constituted normal. The fifth cubital, absent in 



FIG. 1. WING OF GOLDEN PLOVER (AFTEB GOODCHILD). 



1-1', posterior border ; 2-2', anterior border ; .1, remiges ; fi, greater whm coverts : ' '. L>. 

 median coverts: E, /', rrmuiniiiir euverts. 



the wild duck, is often present in birds. The terms ' quin- 

 cubital ' and ' aquincubital ' have been devised to express 

 these facts. The following groups are quincubital : ' 



Crypturi, Galli, Rhinochetidae, Cuculi, many Picarians. 

 On the other hand aquincubital birds are 



ColymbidaB, Tubinares, Steganopodes, Herodiones, Acci- 

 pitres, Anseres, &c. 



The majority of birds, in fact, have not the fifth cubital 

 remex. The most remarkable fact about this missing 

 rernex is that it is either absent or present ; in no case are 

 there any intermediate conditions, such as a small remex. 



See SCLATEB, 'Remarks on the Fifth Cubital Remex,' &c.. Ibis (6), ii. 1890, 



p. 77. 



