Kappers, Eversion of Brain Wall. 435 



exactly defined; and he with Friedrich Meyer regarded the 

 olfacto-habenular tract, which in Cyclostomes for the greater 

 part originates in the palaeo-palhum, as a homologue of the cor- 

 tico-habenular tract of Reptiles and Mammals, not making an 

 exact distinction between the pallium of fishes and the archipallium 

 of higher vertebrates, which was not right, an archipallium and 

 archicortex being entirely absent in the former. Amongst others 

 Prof. J. B. Johnston criticised this point of Studnicka's work 

 and I can only join him in this.^ 



Referring for the description of the forebrain tracts in different 

 animals (I studied the vertebrate series from the Cyclostomes 

 to the Chiroptera) to my work in the Folia Neuro-biologica, I 

 here only want to draw attention to the fact that the differences 

 above mentioned for the dorso-lateral forebrain w^all also occur 

 in other parts of the brain. 



Fig. 5. 

 Fig. 5. Frontal section through the medulla oblongata of Chima?ra monstrosa. 



If we compare figs, i and 2, which represent two different 

 forebrain types (Galeus canis and Amia calva) with figs. 3 and 

 4 which are made after sections through the medulla oblongata 

 of different Plagiostomes, we see at once that the same contrast 

 concerning the form of the dorso-lateral v/all is also present between 

 the hindbrain of Galeus canis on one side and Hexanchus griseus 

 on the other. 



The nucleus of the nervus lateralis anterior, which in most 

 sharks is bent inward, so that it lies under the cerebellum, is 

 turned outward in Hexanchus, and Chima^ra monstrosa (fig. 5) 

 exhibits a character which keeps about the middle between these 

 extreme forms, as the same nucleus, though inverted, is not nearly 



3 On the other hand I do not consider Professor Johnston's nomenclature, as far as concerns this 

 question, very happily chosen, as he would better make a difference between the epistriatum of fishes 

 and the primitive mantle-portion, palaeo-pallium, which morphologically are very different things. 



