544 Journal of Comparative Neurology and Psychology. 



twigs are possibly the "rr. cutanei jugulares" mentioned by 

 Druner. From the descriptions of Fischer, Kingsley and 

 Druner, we are led to infer that the two jugularis branches that 

 pass back through the depressor mandibulae muscle are distinct 

 from each other, but in fact they anastomose. In the dorsal one, 

 the r. lateralis VII which may be double, there are motor fibers 

 associated with the laterahs fibers. The ventral one, primarily 

 motor, may be exclusively motor or it may contain lateral line 

 fibers also. I have not been able to demonstrate general cutaneous 

 fibers in these; in fact in the r. laterahs VII I have been able to 

 demonstrate beyond question that in some individuals no general 

 cutaneous fibers can possibly be present until it receives the 

 branch from the nerve that supplies the sphincter colh muscle. 

 As noted above, it is not impossible that the r. lateralis VII after 

 it has emerged from the muscle may contain general cutaneous 

 fibers. Cross-sections of the main nerve show scattered among 

 the intensely black-stained laterahs fibers that compose the bulk 

 of the nerve some lighter colored ones. It may also contain com- 

 munis fibers, but I have detected no evidence of this. 



7. the glossopharyngeal and vagus nerves. 



a. The roots of the IX-X complex. — ^The IX-X complex in 

 Amphibia is generally described as arising by five roots, but care- 

 ful comparison by determination of components shows that the 

 roots described in one species by one writer do not always corre- 

 spond to the roots of a second species described by another writer. 

 Hence a statement that in general the IX-X complex in Amphibia 

 arises by five roots requires some qualifications. In Amphiuma 

 the IX-X nerves arise from the brain by five roots, or rather 

 groups of rootlets (fig. i); but these roots do not correspond in 

 detail to those described in Necturus by Kingsbury, nor to those 

 in Amblystoma as described by Coghill. The five roots are 

 those mentioned by Kingsley. The first group of rootlets (figs. 

 I, 10 and 23) is composed of laterahs (X(j)), communis {IX (i)) 

 and motor {IX (2)) fibers. The communis and motor fibers after 

 passing through the ganglion form the glossopharyngeal or first 

 branchial nerve, with the exception of the general cutaneous com- 

 ponent in the latter. The lateralis component supplies all the 

 lateral fine fibers of the vagus group. This lateralis component 



