CoGHiLL, Cranial Neri'es of Ambly stoma. 277 



the teleostean pseudobranch proves to be a hyoidean 



demibranch, rather than mandibular, then the posterior palatine 

 must be the post-trematic branch of the facialis, if it is a bran- 

 chial nerve at all." In the same discussion Cole proposes that 

 the Jacobson's anastomosis in teleosts is the pre-trematic IX 

 with fibers from the facialis (posterior palatine). 



Now, if the so-called Jacobson's anastomosis of Ambly- 

 stoma represents that of fishes, how can we account for the r. 

 pre-trematicus IX which appears in Urodela in addition to the 

 glossopharyngeal branch to the anastomosis ? It is possible 

 that my second branch of the t. glossopharyngeus, which forms 

 the anastomosis with the r. palatinus caudalis, represents a part 

 of the r. pre-trematicus, since the latter nerve sometimes arises 

 in part from the second branch. Again, there is sometimes in 

 Amblystoma, and also in Triton (Druner), a small branch of 

 the facialis which anastomoses with the r. pre-trematicus IX. 

 This anastomosis in reality corresponds more closely with 

 Jacobson's anastomosis of teleosts, if Cole is correct in his 

 view that the glossopharyngeal branch concerned in teleosts is 

 pre-trematic. Furthermore, the nerve resulting from the 

 Jacobson's anastomosis of Urodela passes far cephalad in the 

 roof of the mouth while the r. pre-trematicus IX holds a 

 typical position in the hyoid arch. 



Herrick believes that the glossopharyngeal branch to the 

 anastomosis in the cod fish is the palatine branch of the nerve. 

 This, I believe, is the case in Amblystoma, since the nerve 

 gives off numerous twigs to the pharyngeal epithelium. How- 

 ever, it cannot be affirmed that the so-called Jacobson's anas- 

 tomoses of Urodela and fishes are homologous structures until 

 their relations are better understood in both forms. 



5 . — Rami Pre- trematici. 



A statement made by Platt ('96, pp. 532,3) concerning a 

 "pre-trematic" nerve in Necturus is open to some question. 

 This writer says: "The lateral branchial nerve, which, as in 

 the younger embryo, extends backwards and outwards, now 

 fuses" with a pre-trematic branch from the first vagus nerve. 



