MOTOR NUCLEI IN PHYLOGENY 549 
subsequently. The influence exercised upon the feeding re- 
flexes, and consequently upon the pattern of the motor nuclei 
involved, by the development of a tooth-bearing apparatus in 
the pharynx must also be great among teleosts. Especially 
must this be so among those forms in which this structure 
becomes functionally of much more importance than the buccal 
teeth. 
In Ameiurus the mm. levatores branchiales from the fourth 
to the seventh are innervated by branchial branches of the vagus 
and become inserted into the superior pharyngeal bone to which 
they “impart a rocking motion . . . . which must be 
very effective in grinding the food against the inferior pharyn- 
geal’ (McMurrich, 82). The nicety of the reflex adjustment 
of the pharyngeal ‘masticatory’ apparatus in this animal has 
been aptly described by Macallum in part as follows: ‘‘When the 
epipharyngeal pads are touched . . . . the pads are thrust 
down, and at the same time those of the floor are elevated in 
opposition. This is for the purpose of comminuting the food 
as it passes into the oesophagus, mere contact of food or other 
matter serving to bring the pads into action” (80, p. 388). 
In Gadus (39) the muscles moving the pharyngeal bones 
appear to be arranged on quite another and more simple plan, 
and they are also differently innervated. From Herrick’s de- 
scription I gather that the condition in Gadus closely resembles 
that in Menidia, in which the pharyngo-branchial bones are 
moved by but two muscles, viz., the first and second internal 
levators of the branchial arches. The first levator, which is the 
smaller, is innervated by the IX nerve and acts both as a levator 
and a protractor, while the large second muscle receives its 
nerve supply from the vagus and serves simply as a protractor. 
Such variation in the relative complexity of this musculature, 
as well as its nerve supply, is to be expected in view of the fact 
that the tooth bearing plates in question are not developed in 
connection with definite branchial arches but only become 
attached to them secondarily (McMurrich, 81). 
From such scant data as the above it is only possible to point 
out that in Ameiurus and in Gadus when different muscle com- 
