THE NERVOUS SYSTEM 



419 



tion is accompanied by blood-vessels, and by division forms 

 three chorioid plexuses, a median one for the third ventricle 

 (the tela chorioidea of human anatomy) and the two lateral 



d e f 



FIG. 117. Dorsal views of vertebrate brains, corresponding to the lon- 

 gitudinal sections given in plates IV and V. 



(a) Selachian (dog-fish), (b) Teleost (sculpin). (c) Amphibian (frog.) (d) Rep- 

 tile (turtle), (e) Bird (sparrow), (f) Mammal (cat). 



I, telencephalon; II, diencephalon; III, mesencephalon ; IV, metencephalon; 

 V, myelencephalon. In (f) cerebrum and cerebellum have been drawn apart to 

 expose the mid-brain. 



