278 - Journal of Comparative Neurology. 



This is the only pre-trematic branch as yet found in Necturus, 

 The two nerves after their fusion supply the lateral musculature, 

 the vascular system, and the skin, including the external gill." 



The statement that this nerve which is called "pre- 

 trematic" participates in the innervation of the external gill 

 and the muscles shows conclusively that it is not a pre-trematic 

 nerve in the- strict sense. It is, without doubt, my fifth branch 

 of the first t. branchialis X, which has nothing to do with the 

 gill arches or the gill clefts, and on that account cannot be 

 ranked as either a pre-trematic or a post-trematic nerve. The 

 fact, also, that Druner finds a typical pre-trematic branch of 

 the first branchial X trunk in Menobranchus is additional 

 evidence against Platt's interpretation of this nerve. 



The series of pre-trematic rami of the glossopharyngeus 

 and vagus which I have described for Amblystoma has been 

 found by Druner, also, in Salamandra and Triton. The first 

 two nerves of the series have been observed, also, by Druner 

 in Proteus and Menobranchus. It seems certain, therefore, that 

 these nerves are typical for Urodela. Furthermore, they seem 

 to be strictly homologous with the pre-trematic nerves of fishes, 

 and their discovery proves a closer relationship between the 

 branchial innervation in fishes and Amphibia than was formerly 

 recognized. 



The anastomoses which I have described between the pre- 

 trematic and post-trematic rami in each of the three anterior 

 branchial arches have not been observed in other Urodela. 

 The anastomosis in the hyoid arch between the pre-trematic IX 

 and a small nerve (my "facialis A") from the t. hyomandibu- 

 laris is found also by Druner in adult Triton. Druner (p. 573) 

 considers that this nerve may represent a vestigial, sensory r. 

 post-trematicus of the facialis. 



The anastomosis of the first branchial arch between the r. 

 pre-trematicus of the first t. branchialis vagi and the twig from 

 the t. glossopharyngeus, which is the strongest and most con- 

 stant of the series in /^mblystoma, may be comparable to an 

 anastomosis between the pre- and post-trematic nerves of the 

 first branchial arch in Amia (Allis, '97, p. 687) and in Menidia 



