The Myology of Chimpanzee and Baboon. 435 
reaches well up into the thoracic region, while in man it has occa- 
sionally been found to extend asfarup asthesecondrib. Bardeen 
says that a more primitive condition, in which the muscle extended 
to the neck, is frequently indicated in man by aponeurotic slips 
or muscle slips on the upper part of the thorax. In my Macacus, 
I find the rectus abdominis extending up to the fifth rib. 
The Subclavius is found in the chimpanzee to arise from the 
first rib 3.5 em. from the sternum, by a short tendon. The belly 
is .75 cm. in diameter. Its fibers are inserted into the distal half 
of the clavicle. Some of these fibers are closely related to the 
conoid ligament. In the Macacus, this muscle is applied to the 
clavicle for most of its length. 
Vrolik found this as in man; Beddard describes it asinserted on 
‘the proximal half of the clavicle and ensheathed by the coraco-clavi- 
cular ligament. In his orang, Hepburn found an additional slip 
from the second rib, while in the orang of Primrose it was in no 
way continuous with the coraco-clavicular ligament, and was 
poorly developed. 
In the chimpanzee, I also find a Sterno-chondro-scapularis aris- 
ing as a tendon inserted into the first rib, and affixed to the cora- 
coid process internally to the attachment of the short head of 
the biceps. ‘The only muscle fibers that occur are in a small 
eroup at the coracoid attachment, and in a still smaller one at 
the costal insertion. Champneys describes such a fibrous band 
and notes a partial fusion with the subclavius at the anterior 
end. He quotes Rolleston as calling this the representative of 
the long coracoid of birds. Le Double reports it as occurring in 
man in two out of forty cases. 
The Deltoideus presents only slight irregularities. In the chim- 
panzee and in the baboon, the connection between its most ven- 
tral border and the clavicular portion of the pectoralis major is 
unusually close. In the baboon, the short attachment of the 
pectoralis to the clavicle gives the deltoideus a remarkable long 
clavicular origin. 
Champneys and Michaélis say that it arose from nearly all 
the clavicle in their baboons, while Hepburn states that the close 
joining of the deltoideus with the clavicular portion of the pec- 
