12 ALLEN’S NATURALIST’S LIBRARY. 
for the upper jaw, and the sphenoidal fissure, which gives 
exit to the third, fourth and sixth cranial nerves, have but 
one aperture, as in the Rabbit, which belongs to the 
Rodentia. 
The sacral vertebre are generally three in number, and the 
lumbar and dorsal together vary from nineteen to twenty-three. 
The brain, as Sir William Flower has observed, departs con- 
siderably from the form of what may be called the primatial 
type, and approaches in form to that of the carnivorous 
animals. The hind-brain, or ceredel/um, is not completely 
covered by the cerebrum. The latter has but few convolu- 
tions (indicating a low intelligence), but its posterior lobe is 
always present, though more or less rudimentary, and so also 
are many fissures, which are characteristic of its surface in 
the higher Primates. The olfactory lobes are usually large and 
not covered by the cerebrum. 
The uterus and structures for the nutrition of the young 
prior to birth are low in type, and approximate to the condi- 
tions seen in the Pig, the Horse, the Chevrotains, and the 
Ruminants. The unborn Lemur is often encased (as among 
the Sloths) in a skin-like covering (epitrichium) which breaks 
into patches before birth. 
The tongue has a horny supplementary under-tongue (szd- 
lingua) attached beneath it. The stomach is simple, not 
formed of several compartments. ‘The transverse portion of 
the great intestine is convoluted in a remarkable manner upon 
itself, the caecum also being very large. ‘The main arteries of 
the arm and leg break up (as in the Sloths) into an immense 
number of small vessels (called vetia mirabilia) parallel to one 
another instead of being simple branching trunks. 
The long tendons of the muscles for flexing the digits (the 
