132 THE GENERAL ANATOMY OF THE CERCOPITHECIDAE [SECT. A 



in animals with quadrupedal structure) have not been far en- 

 croached upon by pronation and supination. The angle of torsion 

 of the humerus amounts on the average to about 100° (cf. Broca's 

 figures : Carnivora, average angle 95° ; European, 161°). The 

 carpus retains a distinct os centrale : the pollex is very short, 

 owing chiefly to the diminutive size of the phalanges. 



The pelvis is transversely narrow (like the " thoracic cage ")„ 

 the ossa innominata being elongated antero-posteriorly, i.e. as 

 measured from the crest of the ilium to the tuber ischii; they 

 thus are strongly contrasted with the corresponding bones in Man. 

 The pubic symphysis is long, and indeed so extensive that the 

 ischial bones come into contact. Thus the symphysis is really 

 pubo-ischiatic. The tuber ischii is large and everted. 



The femoral head is small, and the neck short in comparison 

 with that of the human femur. There is a very distinct linea 

 spiralis in some cases, but the linea aspera is only feebly developed. 

 Inferiorly, the lack of transverse width is characteristic, while the 

 curvature of the condyles, when regarded from the side, is more 

 nearly semicircular than in the case of Man. The patella is narrow 

 and plays equally on each condyle. Commonly a sesamoid bone is 

 found in the outer head of the gastrocnemius muscle. 



The tarsus is flattened, and its constituents similar in number 

 to those of the human tarsus : the hallux is very short when 

 compared with the other digits : this is chiefly due, as in the 

 manus, to the shortness of the phalanges. 



F. Muscular System 1 . 1. The M. platysma is a strong and 

 extensive sheet, traceable backwards to the middle line of the neck 

 and upwards to the zygoma ; below this it is attenuated locally 

 where the cheek pouch passes outwards. In the axillary region, 

 the M. dorso-humeralis is as distinct as in the Lemur or in Tarsius. 

 In a Cynocephalus mormon dissected by me, nerve-fibres were 

 supplied to this muscle from the inner cord of the brachial plexus, 

 and also from the lateral branch of the second thoracic nerve. 

 According to Ruge the M. sphincter colli is well developed. 



1 The descriptions are based partly on dissections of Cynocepbalous monkeys. 

 Eight subdivisions of the musculature are distinguished, and are the same as those 

 employed in the case of the Lemur (v. p. 77 supra). 



