515 



the complex problems, which the study of the diversely modified forms 

 of brain found in the fish-like Vertebrata has presented for solution. 

 Moreover the recognition of the fact that Lepidosiren and Protopterus 

 possess such a highly-developed cerebral cortex suggests a renewed 

 study of the amphibian brain and an enquiry into the reasons which 

 have brought about the curiously unexpected fact that in respect of 

 this character the Dipnoi come nearer to the Amniota. 



Formatio pallialis 



Mesial edge of 

 hippocampus 



Corpus para- 

 termiuale 



Corpus striatum 



Tuberculum olfactorium 



Fig. 1. A coronal section through the left cerebral hemisphere of an adult Lepido- 

 siren paradoxa Fitz , a short distance in front of the lamina terminalis. (Graham 

 Kerr's section 148 c, 37.2.) X circa 10. 



For all the photographs reproduced here I am indebted to Prof. Graham Kerr. 



At the present time I do not propose to follow up these lines 

 of investigation, but merely to call attention to certain peculiar features 

 of the brain of Lepidosiren and to briefly discuss some points of con- 

 siderable importance as a basis for comparing the cerebral hemisphere 

 in different vertebrates. 



The main facts in the developmental history of the brain of 

 Lepidosiren have been so lucidly and concisely presented by Graham 



33* 



