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rOPULAR SCIENCE REVIEW 
that forms zoologically distant sometimes resemble each other 
in brain-characters, while closely allied forms strangely differ. 
Thus, as M. Gratiolet has pointed out, the “ bridging convo- 
lutions ” between the parietal and occipital lobes re-appear in 
the Spider Monkeys, while two species of Sapajou {Cehus\ 
so closely allied as to have been sometimes treated as one 
species, differ strangely from each other in this respect. 
Again, much stress has been laid, by some writers, on the 
great relative extension backwards of the hinder parts of the 
cerebrum and cerebellum in man. But in the little Squirrel 
Monkey of America the cerebrum extends backwards beyond the 
cerebellum, much more than it does in ourselves, while in that 
remarkable species of Hylohaies — the Siamang Gibbon (which is 
so man-like in its chin, and which exceeds man in the breadth 
of its sternum) — the cerebrum is so short as to leave the cere- 
bellum very decidedly uncovered at its hinder part. In the 
Howling Monkeys, again, this exposure of the cerebellum is yet 
greater, and, nevertheless, these monkeys belong to a family 
in which, as we have seen, the overlapping of the cerebellum 
by the cerebrum attains its maximiun of development. 
Yet the psychical powers of different Apes are very similar. 
Hot only the lowest Baboons of Africa (as e.g. the famed 
“Happy Jerry” of Exeter Change) can be taught various and 
complex tricks and performances, but the less man-like 
American monkeys — the common Sapajous — are habitually 
selected by peripatetic Italians for the exhibition of the most 
clever and prolonged performances. 
As to the two species of Sapajou, the brains of which are so 
different the one from the other, Professor Eolleston asks : 
“Will anybody pretend that any difference can be detected in 
the psychical phenomena, the mental manifestations of these 
creatures, at all in correspondence or concomitant variation 
with their differences of cerebral conformation ? ” 
The difference between the brain of the Orang and that of 
Alan, as far as yet ascertained, is a difference of absolute mass. 
It is a mere difference of degree and not of kind. 
Yet the difference between the mind of Alan and the psychi- 
cal faculties of the Orang is a difference of kind and not one 
of mere degree.* 
Thus on the one hand we see that we may have great differ- 
ences in brain development unaccompanied by any corre- 
sponding psychical diversities, and on the other we may have 
vast psychical differences which it seems we must refer to 
other than cerebral causes. 
See “ Quarterly Eeview,” July 1871. 
