433 
C. J. Sundevall on the Wings of Birds. 
on the ligamentum interosseum; but in Ficus and Pernis it 
is also inserted upon the ulna. 
15. Humero-ulnaris internus, from the condylus internus 
together with the pronator 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 ligamentum 
inter osseum. It is large only in the Gallinse, but occurs 
also in the Anates, Uria, the Psittaci, and probably in some 
others; but is certainly wanting in Strix, 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 
Scliopss 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-ulnares” 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. 
