262 DAVIDSON BLACK 
Casuaris (34) a quite well-marked X—XII intermedius complex 
has been observed, while in Struthio according to Brandis (13, 
pp. 630 and 644), though both vagal and hypoglossal parts of the 
intermedius complex are small, yet there is no doubt as to their 
presence. 
There remains to be considered in this connection those forms 
in which the nucleus intermedius appears to be largely (if not 
entirely) composed of elements of but one type, either vagus or 
hypoglossal, and which fall within groups I or III as defined 
above on pages 238 and 242. 
Unfortunately, the motor nuclei and roots in none of the 
birds constituting group I have been charted, and the only avail- 
able information on the central relations of the motor X and 
XII roots and nuclei is that furnished in Brandis’ description 
(l.c.). The group in question constitutes a quite heterogeneous 
collection of seven forms belonging to no less than five different 
orders (Evans’ classification). Further, with the exception of 
Phasianus and Numida, on the plan of whose syringeal organiza- 
tion I have been unable to obtain details, each of the remaining 
five members of the group is equipped with a well-developed pair 
of intrinsic syringeal muscles. In this respect, therefore, these 
birds are as specialized as many of the forms included in group II. 
It may appear that an origin of XII roots largely if not en- 
tirely from the slightly differentiated rostral part of the cervi- 
cal motor column might well be a primitive character in birds. 
On the other hand, the very heterogeneity of the group in which 
this character has been described, as well as the close relation- 
ship evidently existing between its members and those of group 
II, argues strongly against the fundamental importance of this 
feature. It may be concluded, therefore, that, even should 
further investigations confirm Brandis’ observations, the ab- 
sence of a hypoglossal component in the nucleus interniedius 
complex of these forms should be considered rather as a speciali- 
zation away from the type characteristic of group II than as the 
retention of a primitive character. 
The few forms comprising group III, however, all belong to 
a small quite sharply defined and specialized natural group. 
