248 DAVIDSON BLACK 
dorsal motor V nucleus in Ciconia, though in this animal by 
far the larger number arise in the chief or ventral motor V nu- 
cleus. The dorsal motor V nucleus has been observed in Ciconia 
by Kappers (82, 34), but at the time this investigator could not 
satisfy himself of its indubitable motor trigeminal character, 
and for this reason the nucleus in question was plotted in dotted 
lines on his original reconstruction charts. 
An intermingling of motor V and VII nuclear elements has 
been observed in other avian forms by Kappers (Lc.). This 
author also noted that in some forms (e.g., Spheniscus, Chryso- 
mitris, Colymbus) the ventral motor V nucleus was in reality 
a compound of two cell groups, the smaller lying medial to the 
larger. Further, it is probable that the V motor component 
of the combined V—VII motor column, when present, corresponds 
to the more medial of these motor trigeminal cell groups. 
The origin of the motor V nerve in a number of other avian 
forms has been described in detail by Brandis (16). This author 
also distinguished three motor V cell groups which he termed 
the outer (ventral), the middle (which is continuous with the 
motor VII nucleus), and the inner (dorsal) motor V nuclei.’ 
In Cacatua the three motor trigeminal nuclei are situated 
approximately on the same level as their emergent root. This is 
true also to a large extent in Columba, Chrysomitris, and Colym- 
bus. In Ciconia, on the other hand, a considerable portion of 
the motor V nuclear complex lies caudal of the motor V root 
exit level, while in Spheniscus the reverse condition obtains and 
the motor V nucleus is placed largely rostrad the level of its 
root exit. In all these forms the major portion of the motor 
trigeminal nucleus les in a relatively ventral position within 
the tegmentum. In the latter respect the birds thus far examined 
differ markedly from Casuaris, in which the motor V nucleus 
occupies for the most part a dorsal position such as characterizes 
§In Turner’s description (50), however, but two motor trigeminal nuclei 
were distinguished, viz., the lateral motor V nucleus corresponding to the chief 
or ventral motor V nucleus of the present description, and the deep motor V 
nucleus which would appear to be equivalent to the dorsal motor V nucleus 
described above. 
