10 



STBUCTURE 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. — Wisa of Golden Plovek (afteb Goodohild), 



1-1', posterior border ; 2-3', anterior.border ; A, remigas ; S, greater wing ooverts ; C, D, 

 median coverts ; fi, Fy remaining coverts. 



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, Gralli, Ehinochetidse, Cuculi, many Picarians. 

 On the other hand aquincubital birds are — 



ColymbidEe, Tubinares, Steganopodes, Herodiones, Acoi- 

 pitres, Auseres, &c. 



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

 remex. The most remarkable fact about this missing 

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

 there any intermediate conditions, such as a small remex, 



' See SoLATEE, ' Eemarks on the Fifth Cubital Eemex,' &o., Ibis (6), ii. 1890, 

 p. 77. 



