i86o-6i ‘ SCATTER-BRAINED ’ MAMMALIA 
I2I 
suggested, scatter-brained. Then there was the 
brain in which there was a curious apparatus of 
cross fibres that brought every part of one hemi- 
sphere in contact with the other. The next step 
Was where the cerebral hemispheres began to 
increase in size, and there would not be room 
in the skull to contain them if they were not 
folded and packed as we should pack a nap- 
kin in a box. This type of brain, which charac- 
terised a certain class of Mammalia, was called 
the wave-brain. Then there came a sudden and 
marked step in the increase of the relative size 
nnd complexity, number and depth of the con- 
volutions of the brain, which was called chief- 
brain, and marked a fourth well-defined group. 
The loose brain was peculiar to two kinds of 
cfuadrupeds that belonged almost exclusively to 
Australia, and the duck mole and the kangaroo 
might be taken as types of these orders. 
Owen then described the construction of various 
mammals characterised by the different types of 
brain, proceeding from the lowest to the most per- 
fect in regular order. The gorilla he characterised 
the nearest approach to man. It was an animal 
’^bat had been known, from more or less perfect 
Specimens, for the last eight or ten years, and 
from the enterprising traveller, M. Du Chaillu, to 
^hom we owed the most perfect of these speci- 
^ons, he had obtained the skeleton of a full- 
grown gorilla, which was placed in the British 
