MOTOR NUCLEI IN PHYLOGENY 251 
marked ‘reticular’ nucleus occurs within the ventricular gray 
below the level of the trochlear nucleus (fig. 9, k). The sagittal 
relations of these cell groups are shown in detail in the recon- 
struction chart (fig. 12 F, p. 254). 
The oculomotor root fibers in Cacatua become collected on 
the ventral aspect of the nucleus (fig. 10) and then course 
wee Nudl 2 
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Fig. 9 Cacatua roseicapilla. Sketches a to k to illustrate the cellular detail 
at different representative levels from the rostral to the caudal end of the oculo- 
motor-trochlear nuclear column (cf. reconstruction chart F, fig. 12, p. 254). 
Nu. ac., accessory oculomotor cell group; Nu. d.l., dorso-lateral oculomotor cell 
group; Nu. m.d., dorsal part of the medial oculomotor cell group; Nu., m.v., 
ventral part of the medial oculomotor cell group; Nu. r., large cells on medial 
periphery of red nucleus; Nu., ret., spindle-celled reticular cell column beginning 
caudal to the trochlear nucleus; Nu. IV., trochlear nucleus; R. IV., homolateral 
trochlear rootlets. 
obliquely rostrad and ventrad to emerge on the periphery as indi- 
cated in figure 11 (see also fig. 16 D, p. 260). Some of the fibers 
arising in the ventral part of the medial cell group undoubtedly 
decussate, as both Brandis and Kappers have observed to be 
the case in other avian forms. 
The arrangement and differentiation of the oculomotor and 
trochlear nuclear elements in Ciconia is in general similar to that 
