48 NERVE COMPONENTS OF BONY FISHES. 



Johnston ('98, p. 594) describes the sensory trigeminus 

 in the sturgeon as arising from the spinal V tract and from 

 the tuberculum acusticum. The latter fibres apparently 

 correspond with those to the chief sensory nucleus of 

 Menidia and other forms. There is no evidence that they 

 terminate in the tuberculum acusticum proper. 



The " system y " of Goronowitsch ('88 and '96) in 

 Acipenser corresponds to the spinal V tract and the sec- 

 ondary vago-trigeminus tract of teleosts and the fibres 

 which enter the system y in Acipenser from the lobus vagi 

 ('96, p. 9) and in Lota from the lobi vago-glossophar- 

 yngeo-facialis ('96, p. 21) are obviously the secondary 

 and not the root fibres. In Menidia the secondary vagus 

 bundle (of Mayser) follows the inner and ventral side of 

 the spinal V tract, but can always be clearly distinguished 

 from it (Figs. 17, 18, 19, Sec. X). The motor IX and VII 

 roots run between a portion of the secondary vagus bundle 

 and the spinal V. The secondary VIII bundle lies dorsal 

 and somewhat removed from the spinal V (Figs. 18, 19, 

 Sec. VIII). 



II. — The Acustico-lateral System. 



This system includes the nerves which supply the lateral 

 line organs and kindred structures, viz. : the r. lateralis 

 vagi, the VIII nerve and the two lateralis roots of the 

 facialis. Their nerves terminate together in the tubercu- 

 lum acusticum for the most part, and their fibres are very 

 intimately intermingled. 



In the middle portion of the cerebellar peduncles the 

 outer, or molecular, layer disappears laterally, the cere- 

 bellum being bounded on these aspects by the fibrous and 

 granular layers only. These layers are continued caudad 

 into the tuberculum acusticum of the oblongata and 



