BRANCHIAL SENSE ORGANS IN ICHTHYOPSIDA. 107 
32, and the origin of its ganglion from the skin and in 
connection with the branchial sense organ of this segment in 
fig. 42. The main portion of the nerve grows downwards 
behind the cleft, and proceeds to the lateral muscle plates of 
the first branchial arch. 
Later, as the ganglion separates from the skin, the supra- 
branchial nerve is developed. Like other supra-branchial nerves, 
it splits off from the skin in connection with a sensory 
thickening which gives rise to the supra-temporal sense organs. 
Marshall described the course but not the development of 
this branch in the embryo. 
The direction of growth of this nerve is somewhat different 
from that of the corresponding branches of the seventh. It 
grows dorsally and forwards (fig. 51, s. ¢. g.). 
In late stages pre-branchial and pharyngeal nerves are de- 
veloped, but I have no observations as to their mode of origin 
to record. 
It is obvious that the glossopharyngeal agrees exactly with 
the general schema. ‘The sole peculiarity to be noticed is the 
direction of growth of its supra-branchial branch. As in the 
cases of other nerves, the shifting and secondary attachment 
described by Marshall probably occur; I have, however, not 
studied them. 
Nerves of THE Erentu, Nintu, Tents, anp ELevenrH 
SEGMENTS—VaGUS COMPLEX.! 
The actual development of this complex has been fairly 
accurately described by Van Wijhe. However, as in the cases 
of other nerves, he omitted to record some steps in the process 
of development, and referred the actual connection of the 
complex with the skin to a later stage to that in which it first 
arises. 
He further, though describing the connection of the supra- 
branchial branches with the skin, and though figuring the 
1 For the vagus the condition in Torpedo is taken, in which there are at least 
four nerves concerned; in Hexanchus the vagus has five elements, in Heptanchus 
six (Gegenbaur). 
