508 Proceedings of Royal Society of Edinburgh. [sess. 
When the stomach is opened it is found that there is a 
decided difference in the character of the walls in the two portions. 
In the saccular part the wall is much thinner than in the tubular 
segment, and the mucous membrane is all hut completely smooth. 
The tubular portion, on the other hand, has thick walls, and the 
mucous membrane, in addition to being thick, is arranged in a 
number of well-marked folds which run longitudinally. The 
change in the character of the mucous membrane is abrupt, the 
line of demarcation joining the entrance of the oesophagus to the 
notch in the greater curvature which is seen on the surface. The 
manner in which the pylorus opens into the duodenum is an 
exaggeration of the condition as figured in some text-books on 
human anatomy, and is perhaps most easily described by saying 
that it reminds one of the way in which the os uteri projects into 
the vagina. 
The peculiarity in the form of the stomach of Cercocebus , as 
just described, is of some interest since it affords an example of 
the tri-partite condition of the stomach of primates in general. 
Although some attention had been directed to the subject by 
Wurmb (1) and Otto (2), the compound character of the stomach 
in monkeys was first really investigated by Owen (3) in such 
genera as Semnopithecus, Nasalis , and Golobus. Owen described 
the stomach in these monkeys as being divided into two parts 
which, he suggested, probably play different roles in the process 
of digestion. Martin (4) also mentioned a like condition in 
Semnopithecus nasalis ; and it finally became a recognised 
characteristic of the group to which these various monkeys belong. 
Later writers showed that other primates also possessed a stomach 
divisible into two portions, although the external features of the 
division were not so strongly marked as in Semnopithecus. Huxley 
(5), for example, described the stomach of the orang and gibbon 
as being considerably elongated, and having its cardiac extremity 
rounded and its pyloric portion tubular and curved. Flower (6) 
asserted that in the chimpanzee and orang there is a much 
elongated, recurved pyloric portion marked off from the rest of 
the stomach by a constriction. Sandifort (7) had earlier 
figured the stomach of the orang as having the pyloric portion 
separated from the main cavity by a narrow construction. From 
