144 



The Interbrali is the s3Ht of several important, relays 

 betflesn the forebr-iia and the posterior briin-se^ments. 



The thHlanas is but slightly dii ferentiatel. Only two 

 thalamic nuclei are recognizable. The nucleus strati grisei 

 receives fibres, chiefly from the tractus strio-thalamicus; 

 its axones give origin to the tractus thalamo-tectalis. The 

 nucleas genicalatam receives collateral optic terxinations. 

 It is wholly inferior as an optic centre to either the tectum 

 mesencephali of Mustelus, or to the speciali:2e1 geniculate 

 nuclei of higher foriis. 



The t'fo nuclei habenulae are not greatly unequal in size. 

 The lobi inferiores are the seat of a cro/fded group of peculiar 

 neurones. 



The Forebrain is regarded by the author as anticipating 

 the forebrains of higher vertebrates in many respects. A fair- 

 ly well-defined epistriatum is present, the axones from which 

 enter both the striatum and the pallium. The striatum is an 

 olfacto-motor centre; its axones enter the tractus strio-tnal- 

 amicus for tertnination in the thalamus. An accessory bundle 

 of the tractus strio-thalamicus is derived from the nucleus 

 neuroporicus. An additional olfactory centre is provided by 

 the nucleus postolfactorius. 



The pallium has its neurones grouped, without arrangement 

 into layers, chiefly in the pallial eminences. Three varieties 

 of neurones are to be distinguished. The pallium receives 



