424 
C. J. Sundevall on the Wings of Birds. 
margin; towards the body they become longer ; so also in 
Podiceps, Colymbus, A lea, 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 pollicis, 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, hut 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, Tringacese, and Anser; 
and four in the diurnal Rap tores, the Gallinse, 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, hut has the tip free in the Tringarise. 
The Gallinae, 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 he re¬ 
marked that I can see no particular advantage in employing 
them in preference to the much more natural one, plumae 
pollicis ; 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 
