MORPHOLOGY OF THE FOREBRAIN 491 



In the light of the demonstration in this paper that the division 

 of the cerebral hemisphere of Amphibia (and of higher animals) 

 into dorsal or pallial and basal or subpallial parts is primary and 

 has its morphological basis in the configuration of the primitive 

 neural tube antecedent to the evagination of the hemispheres, 

 I think a provisional formulation of a morphological definition 

 of cerebral cortex is possible. The term was originally applied 

 to the dorsal or pallial superficial grey, as distinguished from ven- 

 tricular or central grey and from ventral or basal grey of the 

 cerebral hemisphere, and it is still commonly used in this sense. 

 Its application to the ventricular grey {e.g., of cyclostomes by 

 B. Haller, 'C8) leads to confusion and is objectionable, as is also 

 the designation of superficial grey over the tuberculum olfactorium 

 and other ventral masses as cortex. The classical and prevailing 

 usage finds its justification in the fact that the ventral (subpallial) 

 part of the hemisphere is dominated by efferent pathways for 

 relatively simple direct reflexes (laterally the corpus striatum and 

 lateral forebrain tract, medially the precommissural body and 

 medial forebrain tract) which either directly or by way of the 

 hypothalamus enter into the ventral motor lamina of the neural 

 tube, while the dorsal or pallial part of the hemisphere is the 

 direct continuation of the dorsal lamina of the neural tube and, 

 being only indirectly related with the great efferent centers, is 

 favorably situated to serve the higher non-stereotyped reflexes. 



Accordingly, I submit the following definitions: 



Pallium telencephali — The dorsal wall of the telencephalon, 

 whether membranous or massive, whether evaginated into the 

 cerebral hemispheres or remaining in the telencephalon medium, 

 being bounded behind by the velum transversum, in front by the 

 olfactory bulbs, laterally by the fissura endo-rhinalis and medially 

 in the evaginated hemisphere, by the fissura limitans hippocampi. 



Cortex cerebri— Correlation tissue developed as superficial 

 grey matter within the dorsal (pallial) walls of the cerebral hemi- 

 spheres. 



