NERVOUS SYSTEM 



'57 



beasts of prey, Ungulata, etc.) the convolutions are relatively 

 well developed ; in the Lissencephala the cerebrum does not 

 cover the cerebellum, and the convolutions are either very 

 slightly developed, or are completely absent. To this class 

 belong the Cheiroptera, Insectivora, Rodentia and Edentata. 

 Hermanides and Koppen have published l an admirable work 



Com 



SM 



Cop 



Ccl 3 



S. 



Ccl 2 



Ccl 1 

 Cba 



Cbl 



Tc 



Vq Fp 



FIG. 81. Median section of brain. (Two-thirds natural size.) Vq, Fp, Fourth 

 ventricle ; Mo, Medulla oblongata ; P, Pons Varoli ; Cca, Corpora mam. ; 

 Tc, Tegmentum of grey matter ; H, Hypophysis ; H 1 , Optic chiasma; H 2 , 

 N. opt. ; Let Grey com. bas. ; Cos, Comm. ant. ; Cba, Comm. bas. alb. ; 

 Ccl 1 , Anterior end ; Ccl 2 , Genu ; Ccl 3 , Body ; Ccl 4 , Posterior swelling of 

 corpus callosum ; FM, Foramen of Munro ; St, Septum lucidum ; Com, 

 Median commissure ; SM, Sulcus Monr. ; Cop, Posterior commissure ; Cn, 

 Pineal gland; Lq, Lam. quadrig. ; A, Aqueduct Sylv. ; Fta, Fissura cer. ant. ; 

 Vma, Vel. med. ant. ; Cbl, Cerebellum. 



on the fissures and structure of the cerebral convolutions in the 

 Lissencephala. These two authors, after investigating the 

 brain of the rabbit, rat, mouse and mole, have obtained the 

 following results : 



(i) In these animals there exist fissures so connected with 

 the cortical structure that where they occur either the cells 



1 Archiv fur Psychologie, 37, 2. 



Fta 



.Vma 



