Studies on Avian Anatomy. — II. 
29 
fig. 18) is on the first and second sternal ribs. It inserts on the 
posterior border of the processus sterno-coracoideus. Origin in 
Bubo (St. -co., PI. III., fig. 25) is on the first five sternal ribs. It 
inserts on the outer surface of the processus sterno-coracoideus, runs 
anteriorly close to the base of the coraco-bracliialis posterior to the 
posterior third of the median surface of the coracoid. Origin in 
Aeronautes (St.-co., PI. VI., fig. 51) is on the first, second and third 
sternal ribs. It inserts on the posterior border of the processus 
sterno-coracoideus. 
13. M. subcoracoideus. In Geococcyx (Sub. co., PI. II., figs. 16, 
18, 20) the muscle consists of two parts. A fan-shaped division arises 
from the dorsal fourth of the median surface of the clavicle and 
partly from the anterior end of the scapula. The long, narrow por- 
tion comes from the middle third of the median surface of the cora- 
coid, contiguous to the anterior border of the m. coraco-brachialis pos- 
terior, and from the neighboring surface of the interclavicular mem- 
brane. The two portions unite just before their insertion, which is 
tendinous, on the apex tuberculi medialis humeri, anterior to the 
insertion of the m. coraco-brachialis posterior, and ventral to that 
of the m. subscapularis. In Bubo (Sub. co., PI. III., figs. 25, 28) 
it consists of two portions of almost equal size. One division comes 
equally from the neighboring median surfaces of the coracoid and 
scapula, with some fibres from the clavicle. The other part comes 
from the middle third of the median surface of the coracoid. They 
unite just before their tendinous insertion on the apex tuberculi 
medialis humeri, anterior to the insertion of the m. coraco-brachialis 
posterior and ventral to that of the m. subscapularis. In Aero- 
nautes (Sub. co., PI. VI., figs. 51, 55) it also consists of two por- 
tions, of almost equal size. One part arises from less than a fourth 
of the anterior median surface of the scapula, the other from the 
middle third of the median surface of the coracoid. The two bun- 
dles fuse as they bend under the scapula and are inserted tendin- 
ously on the apex tuberculi medialis humeri, anterior to the inser- 
tion of the m. coraco-brachialis posterior, and ventral to that of the 
m. subscapularis. 
c. Muscles restricted to the wing. 
1. M. propatagialis. This muscle, described by Gadow (1891) on 
page 253, seems to me almost identical with that of m. pectoralis 
pars propatagialis, described by him on page 245. 
Pars propatagialis musculi deltoidei. In Geococcyx the two mus- 
cles have a common origin on the dorso-median surface of the clavicle 
and the neighboring anterior end of the coracoid. They become 
separated only in the distal third of the fleshy mass. 
