NERVOUS SYSTEM 



377 



cerebellum is Tsry small. A posterior choroid plexus covers 

 the roof of the fourth ventricle, and an anterior plexus in con- 

 nexion with the roof of the thalamencephalon projects downwards 



Sp.Tl. 



Fig. 217. — Dorsal (A), ventral (B), and lateral (C) views of the brain of Protopterus 

 anneclens. C, Cerebellum ; C.H, cerebral hemisphere ; Jb.S.E, branches of the 

 sinus endolymphaticus ; In, iufundibuluni ; L.I, lobi inferiorcs ; M.O, medulla 

 oblongata ; O.L, olfactory lobe ; Op.L, optic lobe ; P, pituitary body ; P.B, "pineal 

 pillow" ; S.E, .sinus endolymphaticus ; Sp.c, spinal cord ; Sp.n, spinal nerve ; Vel, 

 velum transversum ; Z, pineal body; IV. V., fourth ventricle ; ii., iii., iv., v., vi., vii., 

 viii. 1, viii.2, viii, 3.4, ix., and x. , roots of the cranial nerves. (From Burcldiardt. ) 



into the third ventricle, and is also prolonged forwards into each 

 lateral ventricle. In Neoceratoclus^ the brain is certainly more 

 primitive and distinctly less Amphibian. As compared with 

 Protopterus the olfactory lobes and the cerebellum are larger, and 

 the optic lobes are paired. The smaller hemispheres are non- 



^ Sanders, Ann. Nat. Hist. (6) iii. 



p. 157. 



