development of the posterior lobes in the Siamang and in the Howling
monkey. Notwithstanding the exceptional brevity of the posterior lobes
in these two species, no one will pretend that their brains, in the
slightest degree, approach those of the Lemurs. And if, instead of
putting Hapale out of its natural place, as Professor Bischoff most
unaccountably does, we write the series of animals he has chosen to
mention as follows: Homo, Pithecus, Troglodytes, Hylobates,
Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix,
Hapale, Lemur, Stenops, I venture to reaffirm that the great break in
this series lies between Hapale and Lemur, and that this break is
considerably greater than that between any other two terms of that
series. Professor Bischoff ignores the fact that long before he wrote,
Gratiolet had suggested the separation of the Lemurs from the other
Primates on the very ground of the difference in their cerebral
characters; and that Professor Flower had made the following
observations in the course of his description of the brain of the Javan
Loris: (75. Transactions of the Zoological Society, vol. v. 1862.)
And it is especially remarkable that, in the development of the
posterior lobes, there is no approximation to the Lemurine, short
hemisphered brain, in those monkeys which are commonly supposed to
approach this family in other respects, viz. the lower members of the
Platyrrhine group.
So far as the structure of the adult brain is concerned, then, the very
considerable additions to our knowledge, which have been made by the
researches of so many investigators, during the past ten years, fully
justify the statement which I made in 1863. But it has been said, that,
admitting the similarity between the adult brains of man and apes, they
are nevertheless, in reality, widely different, because they exhibit
fundamental differences in the mode of their development. No one would
be more ready than I to admit the force of this argument, if such
fundamental differences of development really exist. But I deny that
they do exist. On the contrary, there is a fundamental agreement in the
development of the brain in men and apes.
Gratiolet originated the statement that there is a fundamental
difference in the development of the brains of apes and that of
man consisting in this; that, in the apes, the sulci which first make
their appearance are situated on the posterior region of the cerebral
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