180 JOHN BEARD. 



later stages of the facial the reader is referred to Marshall's works and 

 to the paper by Marshall and Spencer. 



Nerve op the Seventh Segment — Glossopharyngeal. 



This nerve arises from the neural ridge (Balfonr) immediately 

 behind the auditory organ, and grows down the lateral wall of the 

 body to just above the point of origin of the first true branchial cleft. 

 Its fusion with the skin is represented in fig. 32, and the origin of its 

 ganglion from the skin and in connection with the branchial sense 

 organ of this segment in fig. 4-2. 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.t.g.) 



In late stages prce-branchial and pharyngeal nerves are developed, 

 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 Eighth, Ninth, Tenth, and Eleventh Segments — ■ 

 Vagus complex. 1 



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 w T ith the skin to a later stage than 

 that in which it first arises. 



He further, though describing the connection of the supra-branchial 



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) . 



