CHARACTERS OF MAMMALIA. 



269 



The brain has a cerebellum mth large lateral lobes, fig. 142, d, 

 and the grey superficies much folded; the commissural fibres 

 form, as they cross the under surface of the epencephalon, a defined 

 tract or prominence called ^ pons Varolii,' fig. 143, p. The optic 



142 143 



Upper surface of brain, Dasyure. lxxv 



Under surface of brain, Porcupine. 



lobes, fig. 142, e, are medial in position and divided by a transverse 

 furrow. The cerebral lobes, ib. h, are not only united by a round 



145 



Lycnccphalous brain, Woniljat {riiascolomys fusca). Lxx- 



Corpu.a callosum, brain of Beaver, lxx*. 



commissure, but by a * lyra ' and hippocampal commissure, fig. 

 144, m ; from which is developed, in the majority of the class. 



