3 
XIV NERVOUS SYSTEM 
ioe) 
TP 
cerebellum is very 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 
i 
( 4 \ \ 
| A 
i 
K 
Fic. 217.—Dorsal (A), ventral (B), and lateral (C) views of the brain of Protopterus 
annectens. ©, Cerebellum ; (.H, cerebral hemisphere ; D.S./, branches of the 
sinus endolymphaticus ; Zn, infundibulum; Z.Z, lobi inferiores ; J/.0, medulla 
oblongata ; O.L, olfactory lobe ; Op.L, optic lobe ; P, pituitary body ; /.B, “ pineal 
pillow” ; S.#, 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., 
vill. 1, viii.2, viii.3.4, ix., and x., roots of the cranial nerves. (From Burckhardt.) 
into the third ventricle, and is also prolonged forwards into each 
lateral ventricle. In Neoceratodus’ 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- 
1 Sanders, Ann. Nat. Hist. (6) iii. 1889, p. 157. 
