443 
C. J. Sundevall on the Wings of Birds. 
We pass on now to a short description of the muscles in 
some isolated forms which are the most aberrant that I know 
of. 
Cypselus has appeared to me to show a single agreement 
with the Song-birds, namely, in the extremely small extensor 
carpi radialis brevis. It further resembles Hirundo only in 
having & flexor digitorum sublimis, which is nearly as large as 
the flexor carpi ulnaris and commences from the condylus 
internus; but these muscles are not placed as in the Swallow 
and the Oscines generally, but as in the non-Song-birds, the 
former being situated quite on the radial side of the latter, 
separated therefrom by the continuation of the fascia tendinea , 
which is distinctly of equal breadth. Moreover the bellies 
of the muscles are not rounded, but rectilinear, and continue 
fleshy nearly to the carpus. The non-Song-bird type is there¬ 
fore completely retained, but in other respects the course of 
the muscles is very different. 
The extensor carpi radialis longus is unusually broad, and 
commences above at ^ the humerus; the extensor digitorum 
communis is also unusually broad at the root; the extensor 
indicis small, otherwise as usual; the anconceus parvus as usual, 
to \ ; the flexor digitorum profundus inserted on the condylus 
internus lxumeri ! and nearly as large as the extensor carpi 
radialis longus; course of the sinews as usual. The flexor 
carpi radialis commences near the base of the ulna. The 
pronatores are very strong, the upper one something more 
than 4, the lower one rather over f, contracted at the apex, 
not dilated ! The supinator to 
Picus agrees in most respects with the Song-birds, so that 
we need only indicate the differences, all of which show an 
approximation to the non-Song-birds. They are as fol¬ 
lows :— 
a. The pronator inferior has an unusual structure, which I 
have seen elsewhere only in Pernis apivorus; for it is attached 
to the membrana interossea and to the ulna just as much as 
to the radius (in one specimen of Picus major it was only 
attached to the ulna; but in two- others, and in P. martius , 
was as just mentioned) ; it extends somewhat beyond \ of the 
