234 DAVIDSON BLACK 
Cacatua roseicapilla, which is here described in comparison 
with other avian forms, is a member of the subfamily Cacatuinae 
of the family Psittacidae, suborder Psittaci (Gadow, 26; Evans, 
21). Its distribution is restricted to Australia, where it has a 
wide range from New South Wales to the north-coast region 
(Salvadori, 48, p. 132). Among the members of this interesting 
family the fleshy tongue with its intrinsic musculature is rela- 
tively highly developed and the intrinsic specialization of the 
syrinx is also well marked. In these respects Cacatua offers a 
marked contrast to Ciconia alba, which has been restudied in 
the present connection and in which the tongue is rudimentary 
and the syrinx of simple and almost primitive structure (Bed- 
dard, 4, p. 65, et. seq.). 
The motor nuclei and roots have already been studied and 
reconstruction charts have been made in the following avian 
forms: Columba, Ciconia, and Chrysomitris (Kappers, 32); 
Ciconia (Kappers, 33 and 35); Casuaris, Spheniscus, and Colym- 
bus (Kappers, 34). Of these, reconstruction charts of the last 
three are reproduced in the present paper in figure 16, page 260. 
MOTOR ROOTS AND NUCLEI IN CACATUA AND CICONIA 
Nerve XII 
Among birds two nuclei are usually concerned in the origin 
of the fibers which combine to form the hypoglossal roots. These 
nuclei, which have been variously named by different authors, 
consist essentially of a more specialized dorsal cell group usually 
intimately associated with cells derived from the dorsal motor 
X column, and a less specialized ventral nucleus forming the 
rostral extremity of the cervical somatic motor column.! In 
the following description Kappers’ term ‘nucleus intermedius’ 
(33) has been applied to the former complex, in which there is 
usually to be distinguished a visceral portion, the pars vagi, and 
a somatic portion, the pars hypoglossi. For the less specialized 
1On the other hand, Kosaka and Yagita (38) have concluded from their in- 
vestigations that no true hypoglossal fibers take their origin from the rostral 
extremity of the cervical motor column in the birds examined by them (Columba, 
Gallus, and Anas). This conclusion, however, does not appear to be correct. 
