MUSTELUS L^YTS. 213 



and superficialis nerves^ the central origin and composition of 

 these nerves can be considered. 



In Acipenser, Groronowitsch (24) says that the nerve called 

 by him the ophthalmicus profundus trigemini, and which is, 

 as stated above, simply the ramus ophthalmicus superficialis 

 trigemini in the nomenclature of most other authors, arises 

 from the ventro-anterior trigeminal root of the fish, which 

 root is called by him the root of the nerve Trigeminus I. The 

 ramus ophthalmicus superficialis trigemini, or ophthalmicus 

 superficialis facialis of other authors, is said to arise from 

 Trigeminus II, and this latter nerve is said to arise from the 

 medulla by two roots, one dorsal and the other ventral. The 

 ventral root is said (p. 477) to be a thick-fibred, uiotor one, 

 arising from a so-called dorso-lateral tract of the medulla. 

 The dorsal one is said to be a fine-fibred, sensory one, arising 

 from the lobus trigemini. Strong (60, p. 168) concluded that 

 the ventral root of Trigeminus 11, thus described by Gorono- 

 witscli, could not be motor, and he ascribed to it a lateral sen- 

 sory character, the dorso-lateral tract of Goronowitsch being 

 homologised with the tuborculum acusticum of his own and 

 certain earlier descriptions of the medulla. The dorsal root 

 of Trigeminus II, Strong considers as a part of the fasciculus 

 communis system, and not as a lateral line nerve (p. 192). 

 Kingsbury (40) agrees with Strong that the ventral root of 

 Goronowitsch's descriptions must be a lateral sensory one, and 

 he homologises it with a root called by him Vllb in Amia ; 

 that is, with the entire lateral sensory root of the latter fish. 

 He considers the lobus trigemini of Goronowitsch's descrip- 

 tions as simply a somewhat separate part of the tuberculum 

 acusticum, and says that both it and the root that arises from 

 it. Trigeminus II dorsalis, are " absent as such " in Amia, 

 Lepidosteus and teleosts. The fasciculus communis compo- 

 nent of the V — YII complex is, according to him, represented 

 entirely in the dorsal root of the facialis of Goronowitsch's 

 descriptions, he thus diifering from Strong in the root to 

 which this component is assigned. Goronowitsch, in a later 

 work (25, p. 12), refers to Strong's conclusion that the ventral 



