1903. ] BRAINS OF MONKEYS. 15 
The relations of the parieto-occipital and the Simian fissures 
appear to me to be exactly the same in Semnopithecus as they are 
in Nasalis. As a rule, they are perfectly distinct from each 
other; but in two brains the operculum was more fully developed, 
as it is in the Macaques, and thus the two fissures appeared to 
coincide, 
The postcentralis I found to be always present, and on both 
sides, though often asymmetrical. 
In four Semnopithecus brains I find a small furrow running 
between the intraparietal and the Sylvian, which may represent 
the anterior fork of the parallel fissure figured by Kiikenthal 
and Ziehen in several Apes (and lettered a’ in their figures), and 
stated to occasionally occur in Semnopithecus. The existence of 
this fissure, so far as my material allows me to state, differentiates 
the brain of Semnopitheeus from that of Vasalis. 
Dr. Elliot Smith ' has mentioned in one brain of Semnopithecus 
entellus a bifureation of the calearine fissure, such as that which 
is constant, or nearly so, in Macacus and Cercopithecus. I have 
found this well developed on one side (the left) of a brain of 
S. rubicundus, and less marked on the same side of a brain of 
S. priamus, and on the right side of a brain of S. femoralis. It 
may be observed, however, that in Semnopitheeus the T-shaped 
ealearine fissure, when it is T-shaped, is not visible on a dorsal 
view of the undivided brain as it is in Macacus. In the largest of 
the three brains of Vasalis which I have examined, there were 
indications of the same bifurcation on the right side. 
Text-fig. 4. 
Longitudinal median section of brain of Nasalis. 
e, calloso-marginal fissure; Oa, calcarine ; i.p, internal parieto-occipital, 
The inferior occipital sulcus is always less in the Langurs than 
in the Macaques. In one Semnopithecus brain (the left side of 
S. priamus) this furrow showed an unusual character, in that. it 
joined the parallel fissure. The same occurred on the right 
1 Cat. Physiol. Ser. R. C. S. ed. 2, vol. ii. p. 426. 
