148 THE GENERAL ANATOMY OF THE CERCOPITHECIDAE [SECT. A 



of the pouch. Superficially to the M. buccinator may be seen 

 another cutaneous muscular stratum, repre- 

 senting part of the platysma sheet. 



In correspondence with the proportions of 

 the maxillary and mandibular skeleton, the 

 tongue is elongated and presents almost a 

 truncated appearance anteriorly. The tonsils 

 are small. The oesophagus has much the 

 appearance and relations presented by the 

 corresponding human structure, and on its 

 way to the stomach it grooves deeply the 

 posterior aspect of the left lobe of the liver. 

 The latter organ is a simple sac, but in one 

 genus, viz. Semnopithecus 1 , the stomach is 

 extraordinarily sacculated. 



Fig. 93. Sections 

 of upper and lower 

 lip. Cynocephalus, ? . 

 (?Sp.) 



This peculiarity occurs in the Asiatic Semnopitheci, 

 and the African Colobi, being less exaggerated in the 

 latter. Other characters (ex. gr. diminution or ab- 

 sence of cheek-pouches, and excess in length of the hinder limbs over the 

 fore-limbs) are associated with this modification of the stomach, which 

 may be attributed provisionally to the largely vegetarian diet of the 

 animals possessing it. 



The distinctive features seen in an adult Semnopithecus (Nasalis) are 

 shewn in Fig. 94. The enormous stomach dwarfs the thoracic viscera in 

 size, and it has displaced the liver completely from the left hypochondrium 

 and the epigastric region. The liver is modified to an extent rendering it 

 unrecognizable as that of a primate mammal. The spleen has been greatly 

 displaced and is likewise of peculiar form. 



These profound changes are attributable (as suggested above) to the 

 particular diet of these monkeys. This idea is the outcome of observations 

 on the modifications of the stomach in herbivorous mammals of other Orders. 

 But Schwalbe 2 reasonably suggests that the stomach in Semnopithecus is 

 also capable of providing for rumination. If such be the case, the ultimate 

 factor is still a physiological one. And the importance of bearing in mind 

 the influence of physiological factors is again impressed on the student 

 of morphology. Another important reflexion is that the skeleton does 

 not enable us to predict the discovery of such aberrations of the morpho- 

 logical dispositions as we actually find in the perishable viscera here described. 



1 The name Presbytis replaces Semnopithecus in the latest nomenclature. 



2 Z.f. A. u. M. 1912, Sonderheft n. 



