CRANIAL NERVES OF SILURUS AND MORMYRUS 15 
it is not strange to find the same position of the motor V and VII 
nuclei in both. 
Concerning the abducens nucleus not much can be said. The 
III and IV nuclei and roots themselves being small, the VI root 
is hardly recognizable. 
Whilst in all teleosts as yet examined two VI roots and two 
VI nuclei could be detected, I could find only one small root in 
my object, at the level of the posterior rootlet in other teleosts. 
The, corresponding cells have a rather ventral position but can- 
not be easily delimited from the surrounding reticular cells. The 
second (probably more frontal) root and nucleus could net be 
found, perhaps because the ventral border of the bulb was some- 
what damaged on more frontal levels. 
The motor glossopharyngeus root has the typical course found 
in teleosts: It enters slightly frontally and ventrally from the 
level of the corresponding sensory root, and runs in a frontal direc- 
tion near the base of the bulb, bordering the facial nucleus (figs. 
4and 9). At the frontal level of that nucleus it turns in a dorso- 
mesial direction, acquires a position near the fasciculus longi- 
tudinalis posterior, and can be traced backward again along that 
tract until it reaches its place of origin in the frontal pole of 
the dorsal IX + X nucleus. The sinuous course of this root 
thus corresponds with the course described by Mayser"! in the 
cyprinoids, by C. J. Herrick!? in Menidia, and recently by Kap- 
pers! in several other teleosts. 
The sensory glossopharyngeus root enters the brain at the same 
level as the nervus lateralis posterior, from which it is distin- 
guished by the finer caliber of its fibers (fig. 10). In the oblongata 
the course of the root is fronto-dorsal for a short distance (pro- 
ceeding not nearly so far frontaily as the corresponding motor 
root). 
ll Mayser, Vergleichend-anatomische Studien iiber das Gehirn der Knochen- 
fische mit besonderer Beriicksichtigung der Cyprinoiden. Zeits. f. Wissensch. 
Zool., Bd. 36, 1881, p. 303. 
22. C. J. Herrick, The cranial and first spinal nerves of Menidia. Jour. Comp. 
Neur., vol. 9, 1899, p. 250. 
13 Kappers, Weitere Mitteilungen iiber Neurobiotaxis.. No. VII. Ueber den 
motorischen Glossopharyngeus und Facialis bei niederen Vertebraten. Folia 
Neurobiologica, Bd. 7, 1914, p. 383. 
