34 F. L. LANDACRE 
point of exit of the ramus hyomandibularis, however, the fibers 
from the geniculate and from the ventral lateralis VII fuse into 
a compact trunk in which the different components cannot be 
identified. The roots of these two ganglia, as mentioned above 
can be distinguished. 
In form the geniculate ganglion is roughly triangular with 
the root representing the dorsal angle, the origin of the ramus 
-palatinus and the ramus pretrematicus representing the ven- 
tral angle and the r. hyomandibularis representing the posterior 
angle. In the specimen plotted no distinction could be made out 
between general visceral cells and special visceral cells derived 
from the epibranchial placode. In a 20 mm. embryo, however, 
Reed (716) was able to identify these cells and there is, further, 
in the specimen plotted a slight contact between the genicu- 
late ganglion and the ectoderm at the point at which the pla- 
code proliferated cells which were added to the ganglion. 
14. RAMUS PALATINUS AND RAMUS PRETREMATICUS 
These two nerves arise from the ventral angle of the genicu- 
late ganglion where it rests on the anterior face of the spiracular 
gill cleft. Just at the point of emergence of the larger r. pala- 
tinus, a small twig, the ramus pretrematicus (fig. 1, R.Pr.VIJ) 
or ramus prespiracularis VII, arises and immediately divides 
running caudad along the anterior wall of the spiracular cleft. 
Beyond this point the r. palatinus (figs. 1 and 5, R.Pal.VIT) 
passes nearly ventral in direction, dividing into two twigs neither 
of which reaches the endoderm of the pharynx. Both, however, 
pass in a mesial and ventral direction and come into close rela- 
tion with the endoderm. While several of the finer divisions 
of these twigs can be identified last in the loose mesenchyme 
near the pharyngeal endoderm, there is every reason, from the 
behavior of these nerves in other types and the absence of 
muscle primordia in their vicinity, for identifying them all as 
visceral sensory nerves. 
At the posterior angle of the ganglion there is given off, at 
the point where the geniculate ganglion joins the ventral lateral 
line ganglion, a ramus which immediately fuses so closely with 
