526 DAVIDSON BLACK 
between the caudal end of this nucleus and the rostral end of the 
motor V nucleus, the quotient is expressed by 1.8 in both re- 
constructions. Thus, the relative length of the nucleus in ques- 
tion in the two species (Ameiurus nebulosus and Ameiurus 
melas) is exactly the same. It is probable that the nucleus 
which Bartelmez terms “‘nucleus motorius nervi cervicalis I’ 
corresponds to the nucleus of origin of the first occipito-spinal 
motor rootlet of my description and not to the motor nucleus 
of the first true cervical nerve of this form. 
Motor glossopharyngeal nucleus and root (Nu. et rad. mot. N. 
IX). In Solea, the motor glossopharyngeal root, in passing 
from its nucleus to its point of exit, takes the peculiar round- 
about course that appears to be characteristic of this nerve in 
teleosts. The motor IX root arises from cells situated in the 
rostra] part of the VII-IX—X column and passes rostrad for a 
considerable distance alongside the most dorsal bundle of the 
fasciculus longitudinalis medialis. At the level of the caudal 
end of the rostral motor VII nucleus, the fibers of the LX nerve 
pass through this nucleus laterad and ventrad, but do not re- 
ceive any fibers from it. The root then courses caudad and 
laterad to emerge, ventral to the descending trigeminal tract, 
at the level indicated in the chart, figure 40 A. This level 
is somewhat rostrad of the entrance of the sensory radix of 
glossopharyngeus. 
The course of the motor LX root in Ameiurus closely corvre- 
sponds to that obtaining in Silurus (Van der Sprenkel, |. c., fig. 4) 
and differs in no essential way from the course of this root in 
Solea. It would appear, however, that among siluroids the 
‘genu’ of the motor [X root, tends to enclose within its concavity 
a considerable part of the whole motor VII nucleus, while among 
the pleuronectids, a relatively smal] part an of the rostral motor 
VII nucleus lies in this relation. 
This peculiar geniculate course of the motor LX root has been 
described also by Mayser in certain cyprinoids (79) by C. J. 
Herrick in Menidia (34) and in Hippoglossus, Rhombus, Pleuro- 
nectes and Tinca by Kappers, who recently has restudied the 
