1902 - 3 .] Abdominal Viscera of Cercocebus fuliginosus, etc. 527 
transverse to the long axis of the gut. The two segments of the 
valve are about equal in development, and the fraena are very 
conspicuous and run round the entire circumference of the intes- 
tine. Corresponding to the fraena is a marked fraenal furrow on the 
outside of the tube which also completes a circle (PI. III. fig. 6, a). 
There is therefore, both internally and externally, very clear 
indication of the limits of the caecum and the colon. A short 
distance caudal to the ileo-caecal opening there is another fold of 
mucous membrane (in the position marked b in PI. III. fig. 6). 
which is confined to the lesser curvature, and whose presence makes 
the caecum appear to be divided into two compartments, a lesser 
to the right, and a greater to the left of the fold. The question 
is probably in no wise worth raising, but one is led to ask if, by 
any possibility, this fold can in any way be considered as repre- 
senting that semilunar fold of mucous membrane which was long ago 
described by Gerlach (29) as guarding the entrance to the vermi- 
form appendix in man. I am aware that Berry (30) and other 
anatomists are of opinion that Gerlach’s valve is inconstant and of 
no importance. It is perhaps carrying surmise too far, but the 
large size of the caecum in Lagothrix , and its relatively small 
dimensions in the higher primates, leads to the thought of the 
possibility, at least, that the greater part of the caecum here re- 
presents the vermiform appendix of man, and that the limit of 
such a representative may be indicated by this particular fold of 
mucous membrane. That the fold occurs where there is a kink in 
the intestine would remove any possibility of its having a morpho- 
logical significance were its dimensions entirely accounted for by 
the kink; which they are not. Possibly further investigation 
will either explain the meaning of the fold, or show that its 
occurrence is purely accidental. 
Colon . — The colon of Lagothrix is arranged so much like that 
■of man that the terms in use in human anatomy may very well 
be employed in its description. The ascending colon is a wide 
tube with a diameter equal to that of the caecum. In its progress 
cephalwards to the liver, it forms a gentle curve whose convexity 
looks to the right (i.e., it follows the concavity of the abdominal 
wall). At the same time there is another less marked curve, the 
concavity of winch looks ventralwards. The actual lesser curvature 
