513 



Nachdruck verboten. 



The Cerebral Cortex in Lepidosiren, witli comparative Notes 

 on the Interpretation of certain Features of the Forehrain in 



other Yertehrates ^). 



By Gkafton Elliot Smith. 



With 18 Figures. 



The Dipnoan cerebral hemisphere is provided with a pallial form- 

 ation, which is sufficiently well-developed and sharply separated from 

 the ependymal mass of cells to be directly comparable to that found 

 in the Reptilia. This pallial formation or cerebral cortex, as it is 

 displayed in the brains of Lepidosiren and Protopterus, is far more 

 definitely distinguished from the so-called ganglionic masses — corpora 

 striatum et paraterminale — than is the case in any Amphibian brain 

 known to me. 



It is quite unnecessary to insist upon the very great significance 

 of these facts, both to the morphologist, who is seeking to institute 

 exact comparisons between the brains of the Ichthyopsida and Saur- 

 opsida or to find the earliest phases in the evolution of the dominant 

 organ of the nervous system, as well as to the systematist, who is 

 endeavouring to determine the place of the Dipnoi in his scheme of 

 classification and their degrees of affinity to other groups of vertebrates. 



I am well aware of the fact that this observation is not altogether 

 new. So long as twenty years ago Edinger^j^ in commenting on 

 Fulliquet's dissertation (Recherches sur le cerveau de Protopterus 

 annectens, Geneve 1886), which had been published two years before, 

 stated that the outer cell-layer of the Dipnoan cerebral hemisphere 



1) All the observations on Lepidosiren recorded in these notes 

 were made in the Laboratories of the Natural History Department in 

 the Glasgow University on the serial sections of foetal and adult material 

 belonging to Professor Gkaham Kerr, 



2) Untersuchungen über die vergl. Anatomie des Gehirns. I. Vorder- 

 hirn. Abhandl. d. Senckenb. naturf. Gesellsch., Bd. 15, 1888, p. 110. 

 (I quote this reference from Bubckhabdt's memoir on the Brain of 

 Protopterus, op. cit. infra.) 



Anat. Anz. XXXIII. Aufsiitze. 33 



