C. J. Sundevall on the Wings of Birds. 433 



on the lig amentum interosseum ; but in Picus and Pernis it 

 is also inserted upon the ulna. 



15. Humero-ulnaris internus, from the condylus internus 

 together with the p7'onator inferior, of which at first it seems 

 merely to constitute a part ; lies under the flexor carpi 

 ulnaris (No. 8) nearly as No. 6 under No. 5, but not united 

 with it. Inserted upon the ulna beside the lig amentum 

 interosseum. It is large only in the Gallinae^ but occurs 

 also in the Anates, JJria, the Psittaci^ and probably in some 

 others; but is certainly wanting in /S/ri-Z", Pernis, Charadrius, 

 Sterna, Ciconia, Grus, and the Oscines. Some membranous 

 threads, very high up, usually, however, indicate its place. 

 It must be regarded as a continuation of the pronator 

 inferior on the other side of the bone. It is called by 

 Schopss " flexor profundus Gallinacearum,'" which long 

 name, in order to be quite correct, must be further increased 

 by the word " cubiti."" Moreover it is erroneous, as the 

 muscle occurs in several forms. 



16. Brachialis internus (or Flexor antibrachialis brevis) is 

 far less than in man, lies in birds almost entirely on the 

 cubitus, and passes up, on the humerus, only between the 

 two condyles ; on the ulna it goes somewhat further down 

 near the ligamentum interosseum, concealed by all the flexors 

 and under the pronator inferior. It terminates on the ulna 

 near the preceding (15) when this occurs, but is in its whole 

 development without any relation to it, and seems scarcely 

 to vary in size. 



Note. — All the short muscles [b) on the outer and inner 

 sides of the cubitus seem to form together one or two 

 inferior muscular layers, which surround the joint, and are 

 covered by the long muscles which pass to the carpus and 

 fingers. They might all be called " humero-ulnures," and 

 seem all to have, as their original function, the holding 

 together and flexion of the joint. They may therefore be 

 merely developments of the capsular ligament. The near 

 relation between the base of one pair of them and a pair of 

 the long muscles (namely Nos. 6 & 5, Nos. 7 & 3, and 

 Nos. 15 & 14) is to be noted. 



