1902 - 3 .] Abdominal Viscera of Cercocebus fuliginosus, etc. 539 
when the abdomen is opened, there is nothing hiding the intestines 
(PI. III. fig. 6). The duodenum is as devoid of mesentery, and as 
firmly fixed to the abdominal parietes, as it is in Cercocebus. This 
is apparently an advance upon the state in the other Cebidse ; for 
Klaatsch states that the duodenum of Mycetes is more firmly fixed 
than in Cebus ; and in Lagothrix it is evident that it is even more 
adherent than in Mycetes. 
The mesentery has a narrow root, as in Cercocebus , and does not 
present any notable feature. As already stated, the caecum is com- 
pletely covered by peritoneum. The ascending colon, the hepatic 
flexure, and the right part of the transverse colon have only 
an exceedingly rudimentary mesocolon ; the peritoneum being 
reflected from their dorsal face on to the duodenum and the greater 
■curvature of the stomach. The left part of the transverse colon, 
the descending colon, and the sigmoid flexure have a long mesocolon, 
especially the sigmoid flexure. The line of attachment of the 
mesocolon to the dorsal wall of the abdomen is a little to 
the left of the mesial plane. It runs in an oblique direction, 
becoming gradually nearer to the mesial plane as it is followed 
towards the pelvis, and finally reaches that plane at the termination 
■of the colon. 
It is evident that the arrangement of the peritoneum is very 
variable in the Cebidse. I have examined Cebus capucinus , Ateles 
■ ater , and Nyctipithecus trivirgatus , and in all of them I find certain 
differences in the degree of fixation of the duodenum, the 
amount of blending of the mesocolon and the great omentum, and 
the development of the mesocolon in connection with the 
ascending colon. It seems undoubted that, as Klaatsch asserts, 
more than one type of arrangement obtains among the members of 
the family ; and that Mycetes , Ateles , and Lagothrix follow a 
different line from that instanced in Cebus . 
