NoRRlS, Nerves of Amphiuma. 553 



branches runs back to the region where the r. int. -ace. divides 

 into its several branches (figs. I and 12). Here the hypoglossus 

 comes into intimate relations with the r. lateralis ventralis and 

 the r. intestinalis recurrens X, but there is no fusing between 

 them such as Kingsley describes and figures. In some cases 

 there may be a temporary mingling of fibers, but in other instances 

 the distinction between hypoglossal and other nerves is absolutely 

 clear throughout, so that we may confidently deny the occurrence 

 of any anastomosing between the hypoglossal and vagal nerves. 

 From the point of the branching of the r. int. ace. trunk the hypo- 

 glossal nerve runs ante ro-ventr ally, giving off no branches until 

 it reaches the anterior section of the sternohyoid muscle. This 

 it innervates and then runs along in the geniohyoid muscle supply- 

 ing it, to end anteriorly in the genioglossal muscle. The main 

 ventral branch of the second spinal nerve passes posteriorly in a 

 direction nearly parallel with that of the hypoglossal trunk. A 

 short distance posterior to the place of branching of the r. int. -ace. 

 it turns sharply about and running antero-ventrally comes into 

 close relations with the r. intestinalis recurrens X. It receives a 

 general cutaneous branch from the third spinal nerve and then 

 divides into a general cutaneous and a motor division. The 

 general cutaneous branch supplies the latero-ventral skin in the 

 anterior post-branchial region; the motor branch divides into a 

 nerve that runs anteriorly to innervate the anterior segment of 

 the sternohyoid muscle, and a second branch that runs ventrally 

 to supply other sections of the same muscle, after anastomosing 

 with a motor branch of the third spinal nerve. The brachial 

 plexus is formed from branches of the third and fourth spinal 

 nerves. The ramus lateralis ventralis X becomes very intimately 

 associated with portions of the brachial plexus, but it is very 

 clearly seen that no anastomosing occurs, such as Bowers 

 describes (doubtless incorrectly) in Spelerpes. 



9. CONCLUDING STATEMENTS. 



It is evident that the arrangement of the cranial nerves of 

 Amphiuma gives support to the view that this species represents 

 in many respects a primitive amphibian type. The group of 

 nerves here designated as ramus oticus; the nasalis internus V; 

 the clear differentiation of pretrematic, posttrematic and pharyn- 



