Studies on Avian Anatomy. — II. 
23 
the posterior three-fourths of the lateral surface of the sternum. It 
inserts on the ventral surface of the crista lateralis of the humerus, 
and sends down a tendinous slip to fuse with the tendon of the 
biceps, running over the tuberculum mediale. The origin in Bubo 
(Pect,, PI. IV., figs. 30, 37) is on the clavicle, inter clavicular mem- 
brane, carina sterni, except the dorsal third of its anterior portion, 
and from the posterior three-fourtlis of the lateral surface of the 
sternum. It inserts fleshily on the crista lateralis, and fuses with 
the biceps tendon above the tuberculum mediale. The origin in 
Aeronautes (Pect., PI. VI., figs. 50, 53, 55) is on the clavicle, the 
interclavicular membrane, the ventral half of the carina sterni, and 
from the posterior lateral third of the sternum. It inserts on the 
crista lateralis and on the tuberculum mediale. 
Pars propatagialis. See M. Propatagialis. 
Pars abdominalis. This muscle is absent in Geococcyx. In Bubo 
(Ab., PI. IV., figs. 30, 37) the origin could not be made out on ac- 
count of the torn condition of the bird. At its insertion it is fused 
with the pars thoracica on the tendon of the biceps. In Aeronautes 
(Ab., PI. VI., fig. 50) the origin could not be made out. It is fused 
at its insertion with the pars thoracica on the crista lateralis of 
the humerus. 
2. M. supracoracoideus. Origin in Geococcyx (Sup. cor., PI. II., 
fig. 16) is on the interclavicular membrane, dorsal two-thirds of 
the anterior part of the carina sterni, and from the anterior one- 
fourth of the sternum. It inserts on the ventral surface of the tuber- 
culum laterale of the humerus. Origin in Bubo (Sup. cor., PI. III., 
fig. 25; PI. IV., fig. 30) is on the dorsal border of the interclavicular 
membrane, anterior dorsal third of the carina sterni, and on the 
anterior one-fourth of the sternum. It inserts on the humerus an- 
terior to the crista lateralis on the ventral surface of the tubercu- 
lum laterale of the humerus. Origin in Aeronautes (Sup. cor., PI. 
VI., figs. 51, 56) is on the dorsal half of the interclavicular mem- 
brane, half the carina sterni, and anterior two-thirds of the lateral 
surface of the sternum. It inserts on the humerus anterior to the 
crista lateralis on the dorsal surface of the tuberculum laterale of 
the humerus. 
3. M. coraco-brachialis posterior. Origin in Geococcyx (Cor.-b. p., 
PI. II., figs. 16, 20) is on the posterior two-thirds of the lateral bor- 
der and dorsal surface of the coracoid. It inserts on the distal 
end of the apex tuberculi medialis humeri. Origin in Bubo (Cor.-b. 
p., PI. III., figs. 25, 28) is on the posterior lateral half of the cora- 
coid and has a broad tendinous extension down to the fourth sternal 
rib. It inserts on the distal end of the apex tuberculi medialis 
