74 



is nore roandei, A faw club-liks dendrites fiJiate from it 

 for a short distance, branchim? but sparsely. The size of a 

 dendrite is increased at intervals by slif5ht s/»elLinf?s. 



The axone passes downward into the deeper levels of the 

 granular layer, instead of ap.vard. It gives off collateral 

 branches soon after its origin, and it breaks ap into a num- 

 ber of fine ter-ninal twigs before any great distance has been 

 traversed. 



This neurone is homologous vvith the variety described by 

 Golgi ('94) frorn the human cerebellum, and by him made a repr^ 

 sentative of his second tyoe of nerve-cell. The branching of 

 the axone is far less profuse, hoi^ever, than in the mammal. 



We thus see that the granular layer of the cerebellum of 

 Mustelus is marked by the presence of the same varieties of 

 neurones /fhich characterize this layer in higher vertebrates. 

 The morphology is somewhat more simple in the selachian, as 

 should be expected, but it is a suggestive fact that the 

 structural plan of higher forms is here outlined in its essen- 

 tial features. 



4. Supporting Elements. 

 The supporting elements of the cerebellum are referable 

 to both the ependymal and the neurogliar series, the former 

 being limited to the granular layer, and the latter to the 

 molecular layer. The structure in each instance appears to 



