520 Proceedings of Royal Society of Edinburgh. [sess. 
slight notches. The caudate lobule (caudate lobe) has the 
form of an irregular three-sided pyramid, two of whose surfaces 
are concave — one for the right kidney, the other for the 
duodenum. The third surface is convex and in contact with 
the right lateral lobe. The apex of the caudate lobule is pointed, 
and falls short of reaching as far as the border of the right lateral 
lobe. The bridge of hepatic substance spanning the ventral surface 
of the vena cava, and joining the omental and caudate lobules, is 
rather thin, but decidedly conspicuous. 
From the above description it will be seen that the liver of 
Cercocebus does not depart in any essential point from the 
mammalian type as laid down by Flower. 
Spleen (PI. III. fig. 5). — The spleen of Cercocebus is remarkable in 
that, in all essentials, it approximates in form to what Cunningham 
(21) was the first to show is the true configuration of the human 
organ. Prior to the appearance of Cunningham’s paper, His’ model 
had been taken as representing the arrangement of the surfaces on 
the human spleen; these surfaces agreeing with the superficies 
gastrica , superficies renalis , and superficies phrenica as indicated in 
Luschka’s (22) description. Cunningham, from observations made 
upon organs hardened in situ , showed that a fourth surface must be 
added — a “ basal surface ” or superficies basalis. This revolution in 
the conception of the form of the human spleen is of some import- 
ance in the present connection, for we find writers describing the 
spleen of the apes and monkeys as resembling that of man, inas- 
much as there are three surfaces (cf. Symington on the “ Viscera of 
a Chimpanzee” (23) ). Such a description doubtless arose from two 
causes — the then accepted notion of the form of the human spleen, 
and the fact that the viscera of the lower primates had not been 
hardened in situ. That the spleens of the various primates 
described do resemble that of man is no doubt correct, but the 
“ basal surface ” was overlooked in the descriptions. In the paper 
referred to, Cunningham says that the spleen of the chimpanzee 
and orang, among anthropoids, is tetrahedral in form ; and that 
in certain of the Cercopithecidse (bonnet monkey and baboon) the 
same shape obtains. It was, therefore, interesting to find in 
Cercocebus a spleen so clearly resembling that of man. Its 
diaphragmatic surface is, as was to be expected, the most ex- 
