LEPUS 



i53 



which it contains. There is also a band of nerve-fibres which 

 join the two sides of the cerebellum to one another passing 

 ventral to the rest of the hindbrain ; this is the pons Varolii, 



Fig. 66. — Lepus : the brain, seen, A, from the inner side of a longitudinal 

 vertical section ; B, from the ventral side. 

 ac, anterior commissure ; c, cerebellum ; cc, corpus callosum ; ch, 

 cerebral hemisphere ; cq, corpora quadrigemina ; cr, crura cerebri ; fM, 

 foramen of Monro (shown by an arrow) ; h, hippocampal commissure ; he, 

 habenular commissure ; It, lamina termihalis ; Iv, lateral ventricle (cavity 

 of cerebral hemisphere) ; mo, medulla oblongata ; oc, optic chiasma ; ol, 

 olfactory lobe ; p, pineal body ; pb, pituitary body ; pc, posterior com- 

 missure ; pi, pyriform lobe ; pV, pons Varolii ; sc, soft commissure. The 

 roman figures indicate the roots of I, olfactory ; II, optic ; III, oculomotor ; 

 IV, trochlear ; V, trigeminal ; VI, abducens ; VII, facial ; VIII, auditory ; 

 IX, glossopharyngeal ; X, vagus, and XII, hypoglossal nerves. 



peculiar to mammals. The cavity of the 4th ventricle does not 

 extend into the cerebellum, which is solid. The roof of the 

 midbrain bears, not two, but four prominences. That is to 



