MOTOR NUCLEI IN PHYLOGENY 253 
Varanus, Colymbus, and Spheniscus. The latter are here redrawn 
in figure 12 as mirror images of Kappers’ earlier figures (34, figs. 
60, 61, 77, and 78, respectively). The change from the original 
orientation has been made so that in these figures as in the larger 
Fig. 11 Cacatua roseicapilla. Transverse section through the midbrain and 
thalamus at the exit level of the oculomotor roots. Same magnification as 
figure 1. G.72., interpeduncular ganglion; Lob. op., optie lobe; R.JIJ., emergent 
oculomotor root; Tr. b. th.s., tractus bulbo-thalamicus (Wallenberg, 59) et bulbo- 
striaticus (Wallenberg, 57 and 59); Vent. op., optocoele. 
charts the rostral end of the reconstruction will be toward 
the left. To facilitate comparison, the charts in figure 12 are 
arranged so that the rostral end of the trochlear nucleus in 
all cases lies in the same vertical plane. 
