438 
C. J. Sundevall on the Wings of Birds. 
os metacarpi [i. e. on the radial side of the carpal fissure). 
The tubercle upon which it terminates in the Oscines is 
wanting. 
The pronator es are distinctly separated, and stronger than 
in the Song-birds. So also with the supinator and humero- 
ulnaris externus; but these latter sometimes extend no further 
down on the cubitus than in the Song-birds (to \, Sec.), 
because the cubitus is usually much longer. 
The following contains a somewhat more detailed descrip¬ 
tion of the muscles of the cubitus in the forms known to me 
other than Song-birds, exclusive of some which deviate con¬ 
siderably ( Cypselus, Picus , Ostrich, Penguin), and which will 
be referred to separately. 
a. On the Outer Surface. 
1. The extensor carpi radialis longus has a nearly cylin¬ 
drical but short sinew in the Raptorial birds and in Sterna , 
a flat and broad one in most others, especially the Gallinae. 
The belly of the muscle often commences with two parts 
[capita), which remain separate far down in Grus, Ciconia, 
Charadrius , some of the larger Raptores, Mergus, See.; but this 
varies in the different Orders. In Columba it is unusually 
broad at the base and commences high up on the humerus, 
above the condylus externus. 
2. The extensor carpi radialis brevis is very large in 
Psittacus, Columba , the Raptorial birds, the Gallinse, and the 
large Waders (also in Otis and Struthio ). It commences 
from the basis radii and near the basis ulnae, so that its 
aponeurosis forms a regular ligamentum interosseum, and the 
concealed part is as thick as one of the other largest muscles. 
On the other hand it is quite small, as thin as a thread, in 
Charadrius, Anas, Sterna, Uria, and Alca, commencing only 
from the radius; in Grus and Mergus also only from the 
radius, but not so thin. 
3. The extensor digitorum communis; rather flat and broad, 
but thin in the Accipitres, slender in the rest. In the 
Ostrich its sinew gives off no branch to the thumb (see further 
on). 
