530 Proceedings of Royal Society of Edinburgh. [sess. 
form of the abdomen ; but it was thought desirable to call 
attention to it as relating to the observations of Keith (11) and 
Ruge (13) on the change which has taken place in the form of the 
trunk, and the alteration of the ratio of its various diameters, in 
primates. 
The same three surfaces as were distinguished in the liver of 
Cercocebus are to be made out in Lagothrix. It is a matter of 
some importance to notice that the area, devoid of a peritoneal 
investment, is much smaller in Lagothrix than in Cercocebus (cf. 
figs. 1 and 4). Whether the particular specimen of Cercocebus 
which I examined has an unusually large bare area or not, I 
rl.f 
cannot say. But the point is of moment in view of Keith’s state- 
ment (11) regarding the comparative straightness of the line of 
attachment of the dorsal mesentery to the liver of pronograde 
monkeys, and its relation to the presence of well-defined lobes in 
these animals. 
All the fissures of the liver (with the exception of the umbilical) 
are much more complete than in Cercocebus , and this may be 
associated with the difference in the lines of reflection of the 
peritoneum to which attention has just been directed. Both right 
and left lateral fissures reach the neighbourhood of the vena cava 
on the cephalic surface (fig. 4), and to the portal fissure on 
