4 Journal of Comparative Neurology. 



I might however add that in the Selachii during life, as in 

 younger stages in bony fishes and in certain embryonic periods 

 of all vertebrates the cerebellar lamella has a deep longitudinal 

 fmroiv in the median line {sidciis media^ius) where the extremely 

 thin lamella is composed solely of ependyma cells and com- 

 missural fibers. 



I.e. 



n.L. 



Diagram : Cross-section through the anterior part of the cerebellum of Mustelus 

 vulgaris showing the arrangement of the different layers. 



I pass now to a description of my silver preparations and 

 begin with the most characteristic cell group of the cerebel- 

 lum, the 



Purkinje Cells. 



The presence of these cells has been already established by 

 the older investigators (Viault, Sanders and Rohon). Sauerbeck 

 was the first, though, to observe and describe them in Golgi 

 preparations. He speaks of them as follows : " Von der Mem- 

 brana limitans interna ab gerechnet im zweiten Drittel der radi- 

 alen Ausdehnung (der Kleinhirnlamelle) finden sich typische 

 Purkinje-Zellen, die nach innen, d. h. gegen die nicht versilberte 



