272 C. U. Ariens Kappers 



its homolateral división) in bony-fishes however reaches enormous di- 

 mensions, as is shown in fig. I and 2 (tr. t. b. r.), and sends endbranchings 

 in the abducens nucleus [Comp. also Tello). 



Besides these animáis have strong vestibular reflex-tracts at the 

 base of the oblongata, partly ending also in these nucleus {Tello). 



cerebcllum 



ob. lat.ant. 



nucl."Vn sens 



Fig. 3. — Dorsal origin of the abducens roots and dorsal position of the abducens 

 nucleus in a shark (Acanthias), after v. d. Horst. 



The dorsal vestibular reflex-tracts, on the contrary are less developed 

 here, much less than in sharks. 



Figures I and 2 on one side and figure 3 on the other show the great 

 difference in size cf the fase, longitud, post. in sharks, compared to that of 

 bonyfishes and the considerable development of the ventral tecto-bulbar 

 tracts in the latter. 



It is not surprising therefore that in bony-fishes the ventral reflex- 

 tracts are exercising a much stronger influence on the position of the 

 eyem úsele nuclei. 



