PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
21 
the spine of the scapula. A branch of the spinal accessory nerve was 
traced to the muscle. The shortness of the fibres of the trapezius 
muscle in that part of it which extended from the spine of the scapula 
to the occiput, and also of the fibres of the levator anguli scapulae, has 
already been noted as accounting to some extent for the shortness of 
the neck in the Orang. 
The Latissimus dorsi arose from the spines of the lower four dorsal 
vertebrae and the supra-spinous ligament, also from the lumbar apon- 
eurosis and from the iliac crest extending as far forwards as the anterior 
superior iliac spinous process. There was thus no “ triangle of Petit” as 
the latissimus dorsi overlapped the external oblique muscle of the abdom- 
inal wall at its insertion into the iliac crest. The muscle was inserted into 
the humerus in front of the teres major, but at a somewhat higher level 
than that muscle. From the latissimus dorsi, near its insertion, there 
arose from its tendon a strap-like muscle band (1.5 cm. wide), which pro- 
ceeded down the arm to be inserted into the fascia attached to the 
internal condyle and the supra-condyloid ridge of the humerus. This 
has been called by Bischoff the Latissimo-condyloideus. Another 
muscular slip derived from the latissimus dorsi passes on a plane 
posterior to the main part of the muscle, and also behind the slip passing 
to the internal condyle, to be inserted along with the lower part of the 
teres major muscle into the humerus. This slip to the teres major ; 
muscle was found by Hepburn^ in both the Chimpanzee and the Orang- i 
The latissimo-condyloideus or Dorso-epitrochlearis, as it has been 
designated by some authors, occurs in all apes, not only in anthropoid 
apes, but in all apes lower in the scale. It is therefore a characteristic 
muscle of the ape and is always present in these creatures, whilst in 
man it is absent, or only occurs occasionally in a very rudimentary form. 
Thus in man one finds that a muscular slip is occasionally given off from 
the latissimus dorsi and passes downwards to the long head of the 
triceps, to the fascia, or to the internal intermuscular septum of the arm 
(Quain^); this, it js claimed, corresponds to the latissimo-condyloideus 
of the ape. 
The Rhomboideus muscle in the Orang formed a continuous sheet 
arising from the dorsal spine as low as the sixth vertebra, and from the 
ligamentum nuchae, also receiving a very definite slip of origin from the 
occipital bone — the occipital attachment was 2.5 cm. wide. This occi- 
pital portion, although showing a continuous line of origin with the part 
1 David Hepburn, “ The Comparative Anatomy of the Muscles and Nerves of the Superior and In- 
ferior Extremities of the Anthropoid Apes,” Journ. of Anat. and Phys., Vol. XXVI, 1892, p. 152. 
2 ” Quain’s Elements of Anatomy,” edited by Schafer and Thane, Vol. II, part 2, 1892, p. 205, 
