532 DAVIDSON BLACK 
separated. The two bundles arise respectively from the rostral 
and the caudal end of the motor V nucleus. The cells of this 
nucleus are divided into two closely related groups, so that it is 
possible to differentiate rostral and caudal motor V nuclei. A 
similar arrangement of the elements of this nucleus obtains in 
Amelurus melas (Bartelmez, |. c.). 
Both rostral and caudal motor V nuclei are placed ventrally 
in the tegmentum. The caudal nucleus extends over the longer 
‘ ea ee ie 
a "ar ? , 
a ANu Fetoe ues 
- Rag 
> Nuvret. 
Ne 
Fig. 36 Ameiurus nebulosus. Transverse section of brain stem on the 
level of the emergent trigeminus root. Abbreviations: Nuw.sec.com., secondary 
gustatory nucleus; Nu.V.m.(1)., rostral moiety of motor trigeminus nucleus; 
R.V.m., emergent fibers of motor trigeminus root. Other abbreviations as 
before. 
distance sagittally, and is closely related along its dorso-lateral 
surface to the secondary ascending gustatory tract (fig. 33). 
The rostral nucleus is somewhat more dorsally placed, and its 
relations in transverse section are indicated in figure 36. The 
emerging motor V roots pass almost directly laterad to gain the 
surface of the medulla, and in their course, they pass through the 
secondary ascending gustatory tract. 
Oculomotor and trochlear nuclei and roots (Nu. et rad. Nn. IIL 
et IV). The nuclei of the oculomotor and trochlear nerves are 
