268 DAVIDSON BLACK 
Kosaka and Hiraiwa (39) have identified with considerable 
accuracy the muscular localization within the VII motor nuclei 
in Gallus and Anas. The ‘Hauptkern’ of these authors was 
found to be chiefly concerned with the innervation of the m. 
subcutaneous colli; the “Nebenkern’ with the m. mylohyoideus 
posterior (m. hyomandibularis and lateralis of Futamura, 25), 
and the ‘Digastricuskern’ with the m. digastricus (m. depressor 
mandibulae of Adams, 1). With these facts in mind, it will be 
of interest to consider further the V—VII nuclear pattern in 
Ciconia and Cacatua (fig. 16). 
In Ciconia the ‘Nebenkern’ is not represented as a separate 
cell group in correspondence with the fact that the tongue is 
small and not protractile.!* In this form the elements are proba- 
bly incorporated within the dorsal motor VII nucleus which 
represents the ‘Digastricuskern’ of Kosaka and Yagita. The 
ventral motor VII nucleus in Ciconia is larger than that in Ca- 
catua in correspondence with the more extensive development 
of the m. subcutaneus colli in the former animal. 
In Cacatua an intimate association of VII ‘Digastricuskern’ 
and motor V elements occurs in what has been termed in the 
foregoing description the combined V—VII motor nucleus. The 
VII motor elements of the complex are more numerous than the 
V and the ‘Nebenkern’ of Kosaka and Yagita is probably repre- 
sented here by the caudo-ventral prolongation of this nucleus 
described above. 
The full action of the m. pterygoideus anterior in elevating the 
maxilla in birds is not possible except when the mandible is 
widely opened by reason of the contraction of the m. depressor 
mandibulae (Biedermann, 6). Adams (1) has drawn attention 
again to the importance of this action of the m. depressor man- 
dibulae (m. digastricus) in the Psittaci.“ In view of these facts, 
144 When the tongue is very protractile or very thick, the m. mylohyoideus 
posterior consists of two parts termed by Gadow the m. serpi-hyoideus and 
m. stylo-hyoideus, both innervated by the facial nerve (Newton and Gadow, 44; 
Biedermann, 7). 
16 The so-called m. digastricus of birds which is wholly innervated by the 
facial nerve is better termed the m. depressor mandibulae, since it is not the 
homologue of the mammalian muscle of the same name whose anterior belly is 
innervated by the trigeminal nerve (Adams, 1). 
