MOTOR NUCLEI IN PHYLOGENY 529 
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30 
Fig. 32. Ameiurus nebulosus. Transverse section of brain stem at the level 
of the caudal end of the motor facial nucleus. 
Fig. 33 Ameiurus nebulosus. Transverse section of the brain stem at the exit 
level of the motor facial root and rostral abducens rootlet. Compare with 
Hexanchus (fig. 13), where an abducens rootlet emerges on the exit level of the 
motor glossopharyngeus. Abbreviations: Lob.fac., facial lobe of visceral sensory 
column; N.U.1.VII., nervus lateralis; Nw.intermed., nucleus intermedius; 
Nu.V.m.(2)., caudo-ventral moiety of motor trigeminus nucleus; Nu.VII.m., 
motor facial nucleus; R.VI/.s., entering sensory facial root. Other abbrevia- 
tions as before. 
