Literary Notices. clix 



thickness, terminated by a triangular dorsal lamina supraneuroporica 

 whose apex lies in the recessus neuroporicus (Lobus olfactorius impar 

 of Kupffer). 



In the mean time Studnicka has published a paper on the Fore- 

 brian of the Craniota, 1 in which he challanges the current doctrine as 

 established by Mihalkowicz, Rabl-Riickhard and others that the bi- 

 lobed prosencephalon of the Amniota is derived from an unpaired 

 condition, either in the ontogeny or the phylogeny. This author's 

 studies on the development of Petromyzon have convinced him that 

 in this type the hemispheres are paired from the first. If there is at 

 any stage an unpaired condition of the hemispheres, this is secondary. 

 They appear not as evaginations, but as thickenings of the walls of 

 the the brain tube. So also in the phylogeny, Petromyzon is re- 

 garded as the primitive type, the unpaired condition of the selachian 

 brain being very aberrant. In the teleosts the so-called pallium is a 

 sort of tela choroidea of the tractus olfactorius, a secondary and 

 purely special modification. The massive basal ganglia are therefore 

 homologized directly with the hemispheres of Petromyzon. In 

 the unpaired cerebrum of selachians either the lamina terminalis is 

 enormously thickened or else the terma is supplanted entirely by the 

 cerebrum. 



The course of phylogenetic development is summarized as follows: 



? 



Petromyzon 



Myxine 

 Selachii Dipnoi Ganoidei 



Amphibia Teleostei 



Reptilia 



Aves 

 Mammalia 



Burckhardt in a reply to this article 2 corrects some misstate- 

 ments and criticises the author's methods of work A mere resem- 

 blance in cerebral structure is not sufficient basis upon which to draw 

 phylogenetic conclusions. 



'Studnicka, F. K. Zur Losung einiger Fragen aus der Morphologie des 

 Vorderhirns der Cranioten. Anat. Am., IX, io, Feb., 1894. 



2 Bemerkungen zu F.K. Studnicka's Mitteilung iiber das Fischgehirn. Anat. 

 Anz., IX, 15, May, 1894. 



