424 C.J. Simdevall on the Wings of Birda. 



margin ; towards the body they become longer ; so also in 

 Podiceps, Colymbus, Alca, and Uria. In Lestris a third very 

 small series is added on the margin. Larus has "a moderate 

 uniform series and a small one. 



D. The Rest of the Wing -feathers, 

 on the pollex and humerus (and the wing-spur). 



1. Plumce poinds, alula s. ala spuria (thumb-feathers, d), 

 seated upon the pollex. These are usually from two to four 

 rather large feathers, which have the aspect and firmness of 

 true quill-feathers, and reach somewhat beyond the end of 

 the small covert-feathers of the hand. Properly, there would 

 seem to be always four of them, but the two lower ones, or 

 only one, are often soft and exactly resemble the small covert- 

 feathers of the hand. 



In the Song-birds we can generally count only two thumb- 

 feathers, or three when one of the coverts acquires a some- 

 what more definite form. So also in Picus. They are more 

 definitely three in the other Coccyges, Tringace?e, and Anser ; 

 and four in the diurnal Raptores, the Galliuse, the other 

 Waders, and the Water-birds, in which all the feathers of the 

 thumb acquire the quill form. 



In the Song-birds the thumb is free for half its length 

 or nearly to its base ; but in the Water-birds [Anas, the 

 Pygopodes, Larus, and Carbo) it is loosely attached to the 

 hand by skin up to the tip, and in Aptenodytes no trace of 

 it is visible externally. Among the Waders it is completely 

 united in Ciconia, but has the tip free in the Tringariaj. 

 The Gallinse, Raptores, and Psittaci have it nearly half- free. 

 In Cypselus it seemed to be completely united. 



Upon the names of alula and ala spuria it is to be re- 

 marked that I can see no particular advantage in employing 

 them in preference to the much more natural one, plumes 

 poUicis ; and, further, that they have been very much mis- 

 applied both in older and newer descriptions of birds — e.g. 

 in Wagler^s writings, in which they most frequently indicate 

 the great covert-feathers of the hand. 



At the tip of the thumb there is a small claw or nail in 



