438 E. C. MacDowell. 
an irregularity. Gray describes such a muscle in man, and says 
that Dr. Struthers found it in 7.6 per cent of bodies. Macalister, 
Le Double, Wood and Bardeen all found this in about 5 per cent 
of cases. Patterson reports its occurrence as ‘‘occasional.”’ 
Bardeen says it is normally represented by a fascial slip. Hart- 
mann describes two insertions of this muscle in the chimpanzee, 
one into the condyle, the other into the middle or inner head of 
the triceps. He quotes Bischoff as describing in the chimpanzee 
an insertion into the fascia over the biceps; in the baboon, an 
insertion into the intermuscular septum and the internal con- 
dyle. Michaélis found it inserted into the triceps in his orang. 
In the gorilla, Hepburn describes this muscle as arising from the 
coracoid process. 
In the chimpanzee, the Coracobrachialis has two divisions. 
Their common origin is from the tip of the coracoid process, and 
from the tendon of the short head of the biceps, with which it is 
intimately related. The firsc division is inserted into the humerus 
between the insertions of the pectorals and the latissimus dorsi. 
This is accompanied by a strong tendon and tendinous bands, 
which pass through the body of the muscle. At a point 5 em. 
from the origin, the main division becomes separated from the 
belly of the biceps. This division also has tendinous bands from 
which several of the fibers of the biceps take their origin before the 
bellies separate. The insertion of this division of the coracobra- 
chialis extends from the distal limit of the insertion of the first 
division to a point five-sixths of the way down the humerus. 
Distally, it jos the medial head of the biceps by an aponeurosis. 
In the baboon (fig. 1, C.) the proximal division is highly devel- 
oped. It adheres closely to the humerus as a broad flat belly. In 
the Macacus, also, this secondary head is well developed. It arises 
as in the other forms and immediately leaves the common tendon 
to be attached by a fleshy insertion close up under the head of the 
humerus, its fibers being perpendicular to the long axis of the 
humerus. There is complete separation of the parts. The lower 
belly extends straight down to be inserted into the lower third of 
the humerus. 
From the comparison of all mammalian forms, Wood concludes 
