MOTOR NUCLEI IN PHYLOGENY 487 
The arrangement of the reticularis nucleus in Selache and 
Raja thus corresponds both in its general extent and in the extent 
of its subdivisions to the nucleus motorius tegmenti described by 
Bartelmez in Amelurus (I. c.). 
Tr.oc.mot.cruc. 
\ 
R.VII.m.ase. 
XN 
ee 
~\ Fib.arc.ext. 
10 ENE 
Tr.oc.mot.cruc. 
\ 
R.VII.m.asc.. \ 
Figs. 10, 11 and 12 Selache maxima. Outlines of transverse sections to illus- 
trate the topography of the medulla. Figures 10 to 16 drawn to same scale. 
Abbreviations: C.c., crista cerebellaris; F.l.m., fasciculus longitudinalis medialis; 
Fib.arc.ext. ventral arcuate fibers of the acusticum; Lob.lin.lat., lobus lineae 
lateralis; Lob.visc., visceral lobe; N.VI.. abducens root; Nu.par., nucleus para- 
medianus (inferior olive); Nu.sp.occ.m., cells of motor spino-occipital nucleus; 
Nu.VII.m., nucleus motorius N. facialis; Nu.X.m., nucleus motorius N. vagi; 
R.desc. V., descending sensory trigeminus root; R.l.VIIT., root of the posterior 
lateralis nerve; R.sp.oce.m.(1), first spinal-occipital motor root; R.VII.m.asc., 
ascending facial motor root; R.IX.m.asc., ascending glossopharyngeal motor 
root; R.X., vagus root; T’r.oc.mot.cruc., tractus octavo-motorius cruciatus; 
Tub.ac., tuberculum acusticum. 
