ON THE BRAIN OF ATELES PANISCUS 505 
above than below, or having samewhat the shape of a triangle, with its 
apex downwards and forwards, and wholly devoid of sulci. The 
small frontal lobe is divided by the horizontal sulci into the three 
infero-frontal, medio-frontal, and supero-frontal gyri. The antero- 
parietal sulcus is placed very far forward, at the commencement of the 
Sylvian fissure, joins the supero-frontal sulcus, and then sends a 
branch backwards. The postero-parietal sulcus (scissure de Rolando) 
is situated so far back that the antero-parietal gyrus (1" pli ascendant, 
Gratiolet) is exceedingly thick, and it passes backwards, as well as 
upwards, towards the inner and upper margin of the hemisphere, 
close to which it terminates. The postero-parietal gyrus (2° pli 
ascendant) widens superiorly, in consequence of the backward inclina- 
tion of the upper part of the Sylvian fissure, to form the postero- 
parietal lobule (lobule du deuxiéme pli ascendant), which presents one 
or two minor sulci upon its surface, and has its inner edge notched by 
the upper end of the calloso-marginal sulcus. The temporal lobe, 
again, is plainly divided into the usual antero-temporal, medio- 
temporal, and postero-temporal gyri, and the occipital lobe has a 
horizontal sulcus which marks off an infer-occipital gyrus from an 
upper region representing the super- and medi-occipital gyri. In both 
brains I find a distinct occipito-temporal sulcus (scissure perpendicu- 
laire externe), though M. Gratiolet states that this very Simian fissure 
is obliterated in AZeles (2.¢c. p. 76). However, he figures what I cannot 
but consider to be this sulcus in his pl. 10, f. 2. 
Another point on which I am much inclined to differ from M. 
Gratiolet is that which he himself regards as a difficulty—viz. the 
extent of the fissure of Sylvius. I cannot find the “ pli intermé- 
diaire, trés petit il est vrai,’ which he supposes (4. ¢. p. 75) to bound 
the upper extremity of the Sylvian fissure. On the contrary, it 
appears to me to be one continuous sulcus ; and admitting this to be 
the case, it will not be longer than the Sylvian fissure of the 
Douroucouli (Gratiolet, pl. 11. figs. 10, 11). But if this be the fact 
then 6, fig. 4, will be the angular gyrus (pli courbe) and 14, fig. 4, will 
be the second annectent gyrus (deuxiéme pli de passage). 
This interpretation, again, would diverge from that given by M. 
Gratiolet ; but I must confess that, to me, the least satisfactory part 
of this able observer’s treatise is that which relates to the identification 
of the angular gyrus and the annectent gyri, throughout the series of 
the Primates. 
The transverse diameter of the cerebellum (P]. XXIX. [Plate 36] 
figs. 4, 6, 7) is much larger, in proportion to its antero-posterior 
measurement, than in Man, and the sides of the upper surface slope 
