The Myology of Chimpanzee and Baboon. 453 
extensor digitorum communis and from the internal border of the 
fibula down to a point 4 em. from the distal extremity. Itis 
attached to the first metatarsal bone alone. Primrose describes 
a double attachment in the orarg. 
The Peroneus brevis arises from the lower half of the fibula 
between the excensor digitorum communis and the peroneus lon- 
gus. It is connected with these muscles by septa. Its tendon 
is inserted into the tip of the tuberosity of the fifth metatarsal 
bone. From this point, a tendonous slip is continued along the 
phalanges to be inserted cogether with the tendon of the extensor 
digitorum communis into the second phalanx. Owen, in an 
orang, and Vrolik and Beddard, in the chimpanzee, found this 
same arrangement. This extended tendon corresponds to the 
peroneus digiti quinti, a muscle found in the monkeys, which 
in man is frequently found fused with the peroneus brevis, so that 
only its tendon of insertion is apparent (Bardeen). Poirier 
(Morris’s ‘““Anatomy”’ p. 459) considers that all the peroneals 
are varieties of this muscle (peroneus digiti quinti), which in its 
most simple form ‘arises from the distal fourth of the fibula and 
is inserted by a tendon into the fifth toe.” 
The Haiensor digitorum longus in the chimpanzee arises from 
the tibia and fibula, from the interosseous membrane and the 
intermuscular septa between it and the tibialis anterior and the 
peroneals. The tibial belly separates half way down the leg. The 
muscle fibers are inserted into a tendon, which, after passing 
through the second tarsal ligament, divides, sending one branch 
to the second, the other to the third digit. The portions supply- 
ing the fourth and the fifth digits do not separace from each other 
until after passing the tarsal ligament. The tendon for the fifth 
digit is not free from muscle fibers until it passes the second liga- 
ment. This is much like the conditions in man, where there are 
two main bellies, each of which divides just after passing the 
ligamert. Owen, in his orang, found no tendon to the secoad 
digit. Beddard found all four tendons, but the one to the second 
digit was small. 
The Flexor digitorum longus (Flexor digitorum tibialis) arises 
from the whole length of the tibia (fig. 4, D); proximally it anas- 
