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The nucleus has received different names from different workers 

 who did not know that they were dealing with the same thing. 

 Mayseu was the first to indicate the functional relationship of the 

 nucleus, as the end-nucleus of a tract from the vagal lobe, but the 

 name given by him does not tell anything of the function of the center. 

 The same is true of the name later given by Edinger, a name purely 

 descriptive of its position. The name previously used by the writer 

 indicates only a part of the sensory center to which it is related. It 

 would seem well, therefore, to adopt the name nucleus visceralis 

 cerebelli, which indicates its functional relations as well as its po- 

 sition. It in reality lies behind the isthmus and belongs to the cere- 

 bellar segment. From Gaupp's (20) description and figures of the 

 ganglion isthmi in Rana and Edinger's figure for Lacerta (2) there 

 can be no doubt of the homology of the nucleus in fishes, amphibia 

 and reptiles. Whether the nucleus in birds which Edinger says (1. c. 

 p. 94) is related to the optic apparatus is the same, is doubtful. The 

 nucleus has, according to Edinger, not been found in mammals. The 

 writer has suggested (12) that it is homologous with the nucleus of 

 the direct cerebellar tract in man. Since that nucleus is situated 

 deep in the cerebellum beneath the superior vermis, it is possible 

 that in birds also the nucleus is to be looked for deeper in the brain 

 than in fishes. 



The clearing up of the homology of this nucleus and its functional 

 relationships leads to an explanation of the valvula cerebelli of ganoids 

 and teleosts which the writer had already thought probable from its 

 relation to the inferior lobes (tractus lobo-cerebellaris). Some time 

 ago Professor C. J. Herrick said to the writer in a letter regarding 

 the connections of the secondary visceral nucleus with the cerebellum 

 in teleosts : "I suspect that the valvula cerebelli may have been called 

 forth by them". The writer had come to the conclusion that the val- 

 vula cerebelli could not be an inherent part of the dorsal cerebellar 

 structure, because all the lateral lobes and the dorsal and caudal part 

 of the body of the cerebellum in Acipenser and other fishes so far as 

 known, is related to somatic sensory centers and tracts exclusively. 

 The valvula on the other hand receives a large tract from the inferior 

 lobes which are olfactory centers (and gustatory, Herrick) and is tra- 

 versed by the commissure of the nucleus visceralis cerebelli, which gives 

 fibers to the valvula. The valvula seems to be visceral sensory in its 

 functional relations. The conditions in selachians described above give 

 the explanation of the valvula, which is peculiar to ganoids and tele- 

 osts. The decussatio veli of selachians is the homologue of the visceral 



