238 DAVIDSON BLACK 
ventralis XII) in a manner very similar to the mode of origin 
of this nerve in many reptiles (fig. 15, p. 259). 
On the basis of the current descriptions of the central origin 
of the hypoglossal nerve in birds, the forms thus far investigated 
may be arranged in three main groups, as follows: 
Group I. Birds in which apparently the hypoglossal nerve arises 
wholly from the rostral prolongation of the cervical motor column: 
Lophortyx, Phasianus, Numida, Laurus, Anser, Phoenicopterus, Fu- 
lica (Brandis, 13).4 
Group II. Birds in which the hypoglossus arises from both the 
nucleus intermedius XIJI and the nucleus ventralis XII: Anas, Gallus, 
Columba (Kosaka and Yagita, 38;> Koch, 37; Brandis, 13); Casuaris, 
Spheniscus, Colymbus (Kappers, 34); Ciconia; Grus, Machetes, Falco, 
Struthio, Cairina, Corvus, and Passeres without exception, Cypselus 
(Brandis, 1.c.); Gallus embryos (Bok, 11); Columba (Koch, 37; 
Turner, 50).° 
Group III. Birds in which by far the greater part (or all?) of the 
hypoglossal nerve arises from the nucleus intermedius XII: The par- 
rot family, among which two cockatoos (Cacatua roseicapilla and C. 
galatea) and two parakeets (Melopsittacus and Palaeornis) have been 
investigated (Brandis, I. c.). 
Nerves IX, X, and XI 
In Cacatua, as in all other birds examined, the dorsal motor 
vagus nucleus is continuous rostrally with that of the glosso- 
pharyngeus. These two nuclei together form the posterior 
visceral motor column, which in this form is relatively short. 
Though it extends rostral slightly above the exit level of the motor 
IX root, it is not prolonged far as a continuous cell column within 
the closed portion of the medulla and its caudal end falls some 
distance short of that of the nucleus intermedius XII (fig. 16 
D260). 
4In the latter two, the flamingo and the coot, Brandis noted that the hypo- 
glossal roots were small and the central nuclei poorly developed; and the origin 
of some of the nerve fibers from scattered cells representing a dorsal XII nucleus 
could not be excluded. 
5 As already noted, these investigators did not consider that any true hypo- 
glossal fibers had their origin in the cell column described above as the ventral 
XII nucleus (l.c., p. 167). 
6 Turner, however, identified the nucleus intermedius XII as the spinal acces- 
sory nucleus. 
