166 Muscular Variations 
Two supernumerary slips, one derived from the junction of Pectoralis 
minor and abdominalis, the other from the latter muscle nearer the 
insertion, cross the axillary space and insert into a fibrous lamella, the 
caudal slip fusing with the axillary arch. The absence of a distinct 
axillary arch in Hapale must, I think, be taken as a specific character 
without special significance, for the structure reappears so uniformly in 
the remaining Primates up to the anthropoid apes and Man, and is such 
a common variation in the latter, that its position as a distinct myo- 
logical character of the Primate order may well be recognized. 
Il. INTERMEDIATE TYPE. a 
1st Example: Cynocephalus anubis, Olive Baboon, Columbia Univer- 
sity Museum, No. 1243 (Pl. IV, Fig. 6). Im this form, while the 
general arrangement of the pectoral mass corresponds to that found in 
Hapale and the Lemur, individual differentiation of the component 
muscles has proceeded further. The Pectoralis minor has segmented 
as a distinct muscle, both from the Subclavius cephalad, and from the 
abdominal Pectoral caudad. The cleft separating the minor from the 
latter muscle extends nearly to the insertion. The same is, however, 
still common to both muscles into the lateral tubercle and the adjacent 
proximal portion of the shaft of the humerus under cover of the 
Pectoralis major and Deltoid. The axillary arch is more closely ad- 
herent to the underlying margin of the Latissimus and is combined at 
the insertion twith the abdominal pectoral muscle. The Pectoralis 
minor still arises largely from the ventral surface and lateral margin 
of the sternum, but some of the deeper fibres of the cephalic portion 
have obtained an attachment further laterad to the upper costal car- 
tilages. ‘There is no clavicular Pectoralis. 
Cynocephalus is a very representative generalized form of the inter- 
mediate type of the Primate Pectoral group, which obtains with only 
slight species modifications in all the lower monkeys of both hemi- 
spheres. The following characters are to be noted, in comparison with 
the primitive type illustrated by Nycticebus and Hapale. 
1. The complete differentiation of Pectoralis major and minor and 
the sharply defined individuality of the muscles. 
2. This character is accentuated in Cynocephalus by the cranial shift- 
ing of the attachment of the Pectoralis minor along the sternal origin, 
developing a wide and well marked interval between this muscle and the 
abdominal Pectoralis. 
In some of the other Cynomorpha the more primitive extensive 
