Studies on Avian Anatomy. — II. 
27 
lateral border of the scapula, extending from the anterior border 
of the M. subscapularis to the M. pars scapuli-cubitalis. It inserts 
fleshily on the dorsal surface of the humerus between the short 
heads of the M. pars humero-cubitalis, anterior to the insertion of 
the M. latissimus dorsi posterior, extending to the border of the 
foramen pneumaticum. 
7. M. scapuli-humeralis posterior. Origin in Geococcyx (Sc-hu. 
p., PL II., figs, 15, 19, 20) is fleshy from the posterior three-fourths 
of the dorsal and lateral surface of the scapula. It inserts by a 
strong tendon within the border of the tuberculum mediale of the 
humerus between the long and short heads of the M. pars humero- 
cubitalis. Origin in Bubo (Sc.-hu. p., PL III., figs. 25, 26, 28; Pl. 
IV., fig. 33) is fleshy from the posterior half of the lateral surface 
of the scapula. It inserts by a strong tendon within the border of 
the tuberculum mediale of the humerus between two heads of the 
M. pars humero-cubitalis. Origin in Aeronautes (Sc.-hu. p., Pl. VI., 
figs. 51, 52, 54, 56) is fleshy from the posterior half of the lateral 
surface of the scapula. It inserts by a short, round tendon within 
the border of the tuberculum mediale of the humerus between the 
heads of the M. pars humero-cubitalis. 
8. M. subscapularis. Origin in Geococcyx (S. sc., Pl. II., figs. 
18, 20) is fleshy, and anterior to the M. scapuli-humeralis posterior 
on the lateral and median surfaces of the scapula. It inserts ten- 
dinously on the apex tuberculi medialis humeri, anterior to the in- 
sertion of the M. coraco-brachialis posterior. Origin in Bubo (S. sc., 
Pl. III., figs. 25, 26, 28) is fleshy and anterior to the m. scapuli- 
humeralis posterior on the lateral and median surfaces of the 
scapula. It inserts by a strong tendon on the apex tuberculi medi- 
alis humeri, anterior to the insertion of the m. coraco-brachialis pos- 
terior. Origin in Aeronautes (S. sc., PL VI., figs. 51, 52, 56) is 
fleshy, and anterior to the m. scapuli-humeralis posterior from the 
lateral and median surfaces of the scapula. It inserts tendinously 
on the apex tuberculi medialis humeri, anterior to the insertion of 
the m. coraco-brachialis posterior. 
9. M. serratus superficial^ anterior. Origin in Geococcyx (Ser. 
s. a., Pl. II., fig. 18) is fleshy on the anterior border of the second 
free rib betwen its processus uncinatus and the tip. It inserts ten- 
dinously on the ventral border of the scapula dividing the m. sub- 
scapularis into a small M. subscapularis externus and a larger m. 
subscapularis internus. Origin in Bubo (Ser. s. a., PL III., fig. 25) 
is fleshy on the first sternal rib, with a small slip from the second. 
It inserts tendinously on the ventral border of the scapula dividing 
m. subscapularis into a small m. subscapularis externus and a large 
