1877.] The Suessonian Fauna in North America. 97 
‘“‘T owe to the. kindness of Professor Noulet, of Toulouse, the 
possession of a fossil cranium in which I have found the cast of 
a brain still more ancient than that of the Anoplotherium of 
Montmartre, since the fragment comes from the Eocene of the 
Lophiodon of Issel. In the brain of this animal (which I call 
provisionally Brachyodon eoceenus, on account of the slight ele- 
vation of the crowns of the molar teeth), there are no longer 
any convolutions, but only certain folds irregularly defined ; the 
olfactory lobes are much prolonged in front, and the cerebellum 
is entirely separated from the hemispheres. This brain is 
smaller in all respects, and less complicated in its structure than 
that of the Canotherium described by Gratiolet ; but it must not 
be forgotten that the latter animal is from a formation much 
more recent, that is, the inferior Miocene of Allier. 
“In proportion as we approach the present period, the differ- 
ences between the fossil brains and those of living species be- 
come less marked, as has also been observed with reference to 
the elevation of the crowns of the molars. Thus the deer and 
the antelopes of the Middle Miocene of Sansan present many 
convolutions, while the cerebellum remains moderately un- 
covered, and the olfactory lobes are very prominent. In the su- 
perior Miocene of Pikermi the brain of the Hippothertum (Hip- 
parton) shows itself a little less rich in convolutions than that of 
the existing horse; and in a fragment of a skull of a monkey 
from the same locality, which I have been permitted to examine 
in the museum, the cerebellum is less completely covered by the 
hemispheres, and the median vermis is more prominent than in 
the living Semnopitheci of the types most nearly related to those 
of Pikermi. But in order to show more clearly this dispropor- 
tion of the fossil brains in relation to those of living Mammalia, 
it is necessary that comparison should be made between species 
of the same family, or, better still, of the same genus. It has 
been possible for me to verify this point by the comparison of 
two carnivorous animals, the living Viverra genetta, and the ex- 
tinct V. antiqua of De Blainville, from the inferior Miocene of Al- 
lier. From this it appears, that with a cranium one third longer 
and one fourth wider than the living V. genetta, the fossil V. an- 
tiqua has not a larger brain, and that this brain, more attenuated 
in its frontal convolutions, does not extend so far forwards. Ac- 
cording to Gratiolet a great development of the olfactory lobes 
is a character of an inferior type. In fact the more we ascend 
into palzontological antiquity the more we find that the olfactory 
