536 Proceedings of Royal Society of Edinburgh. [sess. 
In both animals the ratio is well within the extremes which 
have been noted in various primates. For, so far as can be 
gathered from different papers on the anatomy of different 
primates, the intestinal length varies from four to eight times the 
body length. It is difficult to compare the figures of the different 
writers, because the length of the body is not always measured in 
the same way. It would be infinitely better if some fixed method 
were adopted ; and it seems more rational to take the length of 
the trunk without the inclusion of the limbs, which are capable of 
different degrees of straightening in various species. 
Arrangement of the Peritoneum. 
In bodies hardened by the injection of formol the arrangement 
of the peritoneum is much more easily followed than in those 
examined in the natural condition. Bearing in mind the fact that 
the peritoneum is not infrequently differently disposed in animals 
with close zoological affinities, and finding that Klaatsch (33), in 
his extensive memoir, does not devote much space to either the 
Cebidse or the Cercopithecidae, a very careful examination of 
Cercocebus and Lagothrix was made. And the result was found to 
justify the trouble taken, since certain particulars of much interest 
were revealed. 
The arrangement of the peritoneum in Cercocebus will be 
described first. The great omentum is exceedingly well developed 
in this animal. It covers the whole intestinal mass very loosely, 
extending even for a short distance into the pelvis. There is no 
difficulty in resolving it into a dorsal and a ventral layer until one 
arrives at a sagittal plane a little to the right of the duodenum. 
To the right of this plane two layers cannot be distinguished. On 
the left side of the abdomen, its margin is free until the spleen is 
reached. Here the usual attachment is observed. But on the 
right side of the abdomen there is a line of attachment to the 
dorsal abdominal wall, to the right of the ascending colon, 
extending caudalwards almost as far as the iliac fossa. Here, as 
just said, the two layers of the omentum cannot be demonstrated. 
When this line of attachment is traced cephalwards, it divides 
into two immediately to the right of the duodenum, and in the 
