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 pronatores 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 \, \, kc), 

 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 Gallinie. 

 The belly of the muscle often commences with two parts 

 {capita), which remain separate far down in Grus, Ciconia, 

 Charadrim, some of the larger Raptores, Mergus, &c. ; but this 

 varies in the different Orders. In Colwnba 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 ulna, 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). 



