150 THE GENERAL ANATOMY OF THE CERCOPITHECIDAE [SECT. A 



found to be sacculated in the human foetus (at the period mentioned above) 

 in a fashion similar even in details to that met with in the adult Sernno- 

 pithecus. The most important inference to be drawn from all this, is that the 

 "simplicity" of the human stomach is secondary and not primitive. This 

 subject will be considered further in the sequel. To return to the Semno- 

 pithecus, I may add that in a foetus or very young specimen (examined by 

 me) having a rectilinear length of 160 mm. from vertex to coccyx, the liver 

 still covers the stomach extensively. But the dilatation is already pronounced 

 and a series of foetal specimens would doubtless demonstrate the whole process 

 of the displacement of the liver and the curious scroll-like deformation under- 

 gone by that organ. In an adult Semnopithecus (Nasalis) the liver has 

 been pressed so far rightwards that it appears actually fused with the 

 diaphragm. Yet this unusual relation is shewn by the foetal example to 

 be secondary. 



A well-developed omentum resembling that of Man, extends 

 downwards over the small intestine, and may be traced to the 

 ascending colon as well as the transverse colon (to which it is 

 limited in the higher types). The small intestine has the same 

 general relations as in Man, being provided with a mesentery, 

 distinct even in the duodenal portion of the gut. The caecum 

 is bluntly pointed, a vermiform appendix failing to develop. The 

 ascending meso-colon should be noticed, and the meso-rectum is 

 distinct and extensive, this part (the rectum) being characteristic- 

 ally straight. 



The liver (Fig. 95) still presents (a) quadrupedal or prono- 

 grade features, but nevertheless it differs from that of the Lemur 

 in certain respects, (b) The peritoneal attachment to the dia- 

 phragm and posterior abdominal wall is still "linear," the "bare 

 area" (characteristic of higher types) not having yet appeared, 

 (c) The incisura oesophagea is variable in form in different 

 genera. In the Cercopitheci it is deep and therefore more 

 primitive, but in the Cynocephali (and in certain New-World 

 monkeys) it is shallow. Thus the shallow stage may be attained 

 by a particular form in widely separated groups ex. gr. in 

 Tarsius as contrasted with the Lemuroidea, and in Cynocephalus 

 as contrasted with the other Cercopithecidae. It recurs in all 

 the highest Anthropoidea including Man. This phenomenon 

 (viz. the repetition of the attainment of a certain conformation, 

 or a detail of structure, in a series of animals capable of 



