164 MR. F. E. BEDDARD ON THE [ Feb. 16, 
slightly bowed and not nearly reaching the rhinal fissure; and 
the single brain of Hyrax dorsalis agreed with these. In the 
remaining brains the suprasylvian fissure was carried on to the 
rhinal. I found an orbital fissure in all of the brains, and in five 
or six there were more or less well-developed traces of a preorbital 
fissure which did or did not join the rhinal fissure and rarely 
jomed the coronary above ; in the latter event the fissure did not 
communicate with the rhinal. 
On the temporo-occipital region of the brain, 7. e. behind and 
below the suprasylvian fissure, T find the existence in var ying pro- 
portionate degrees of three more or less parallel fissures which are 
vertical in direetion—emd not of two only as figured by Elliot 
Smith. The most anterior of these is, however, obviously repre- 
sented by the lowermost section of the supr asylvian fissure figured 
in one of Dr. Elliot Smith’s illustrations*. For I have found in 
some brains where the suprasylvian fissure is as strongly bowed as 
in the illustration referred to, that the suprasylvian fissure ends 
anteriorly in a Y-shaped bifurcation of which in other brains one 
or other limb may be entirely or partly absent. In the brain 
figured by Dr. Elliot Smith 7, as in a brain among those examined 
by myself, the upper anterior limb of the bifurcation is absent ; 
whereas in the second brain figured by Elliot Smith it is, as I 
also have seen, the lower part of the fork which las vanished. 
These three fissures seem to me to vary from individual to 
individual and on both sides of the brain of the same individual 
very often. The principal variations in the specimens examined 
by myself were the following :—The most anterior of the three 
fissures was quite absent or represented by a small rudiment which 
did or did not join either the rhinal or the suprasylvian fissure, 
or finally it effected a complete junction between these two fissures. 
The middle fissure which Elliot Smith letters in his drawings as 
the Sylvian is sometimes longer, sometimes shorter; sometimes it 
starts from the rhinal fissure and is sometimes unconnected with 
that fissure. It is occasionally broken into two smaller fissures. 
lying one above the other. More rarely, it is connected by a 
transverse fissure (¢. ¢. one running horizontally) with the third 
of the three fissures referred to and which Elliot Smith terms 
postsylvian. This fissure again varies very much in length and 
sometimes joins the suprasylvian. Very rarely it joins the rhinal 
below. 
These variations are shown in the accompanying figure (text- 
fig. 10), where not only the differences between one brain and 
another are exhibited, but also those between the two sides of the 
same brain. J imagine that the series selected almost exhausts 
the variations which can occur in this region of the brain. It will 
have been observed in reading the foregoing remarks that nearly 
all the sulci of the brain of Hyrax are subject to variation— 
that indeed only the lateral furrow remains constant. 
* Toe. cit. fig. 1771, p. 299. + Loc. cit. fig. 169, p. 298. 
