417 
C. J. Sundevall on the Wings of Birds. 
very small undeveloped feather-rudiments, covered up by the 
next following perfect feathers. In older birds in the summer 
plumage scarcely a trace of them is usually visible. 
This remarkable structure is so peculiar to those birds 
which have the inferior larynx furnished with five pairs of 
muscles, that I have been unable to find any other form 
except Cypselus which resembles them in this respect; but 
it occurs in the whole of them without a known exception, 
and consequently forms a certain external character for 
them*. In every Song-bird, even when sitting with folded 
wings, and in stuffed specimens, we recognize this deficiency 
at the first glance ; it causes the wing to exhibit only a small 
number of coverts, and these to occupy an inconsiderable 
space in comparison with those in the wings of species 
belonging to other orders (see figs. 10, 11). 
All other birds have these feathers developed. In Ficus 
and Upupa , which of all those which have no song-muscles 
most resemble the type of the Song-birds and seem to con¬ 
stitute the real transition to them, the second and third series 
are fully developed, but the first is incomplete, so that it 
merely consists of a few feathers towards the carpus, and all 
are so short that they project but little over the next follow¬ 
ing ones, and therefore may easily be overlooked in dried 
specimens. Except these I know no form in which they are 
less distinct or perfect. Three series occur in the Psittaci, 
all Raptorial birds, most of the smaller Waders, and in Anas ; 
four in Coracias, Cuculus , Gallinula, Limosa , Lestris , and 
Fuligula; five in Columba , Tetrao, Numenius, Podiceps, Co - 
lymbus, and Larus , as also in Carbo, which has them dark- 
bordered. A more special study of them will no doubt repay 
* I have recently had the opportunity of examining a softened skin of 
Menura lyra , and convinced myself that this bird also agrees perfectly 
with the Song-birds in this respect; it ceases therefore to be a probable 
exception, just like the other two, Ficus and Upupa, which I previously 
regarded as such. On the other hand, I afterwards found that Cypselus 
has these feathers exactly as in the Song-birds, which was previously 
accidentally overlooked, probably on account of the size of the covert- 
feathers which occur. 
