CoGHiLL, Cranial Novcs of Avibly stoma. 259 



r. buccalis VII, is not the homologue of the r. maxillaris of 

 Rana, but is homologous with tlie nerve described by Strong 

 as an "accessory" branch of the trigeminus in the tadpole. 



3. The terminal branches of the r. ophthalmicus pro- 

 fundus in Amblystoma are not homologous with the terminal 

 branches of that nerve in Rana. 



In support of the first conclusion I have shown (a) that a 

 branch from the r. ophthalmicus profundus in Amblystoma 

 anastomoses in the roof of the mouth with a palatine VII 

 branch which is homologous with a nerve fusing with a branch 

 of the maxillaris V in Rana ; (b) that corresponding cutaneous 

 areas are innervated by a part of the r. ophthalmicus profundus 

 in Amblystoma and by the maxillaris V in Rana. 



As to my second conclusion, I have shown that the two 

 nerves under consideration correspond in striking detail (a) with 

 reference to their relation to the Gasserian ganglion, (b) in 

 their relation to the r. buccalis VII, and (c) in their peripheral 

 distribution. 



The extent of the fusion of the "accessory" ramus with 

 the r. buccalis VII is reduced to a minimum in the tadpole 

 while in Amblystoma the extent of the corresponding fusion 

 varies greatly. It may take place immediately outside the 

 ganglion and continue to the region of the eye ; or the two 

 components may not meet until they reach the lateral border of 

 the temporalis muscle. In young Spelerpes, according to 

 Bowers, the two components of this nerve may be distinct 

 throughout their entire extent; and Platt's studies ('96, p. 520) 

 show that the same condition may occur in young Necturus. 

 These observations of Bowers and Platt indicate that Nec- 

 turus and Spelerpes, in this particular, hold an intermediate 

 position between the tadpole and Amblystoma, and afford 

 important evidence in favor of my conclusion concerning the 

 homology of the r. maxillaris V in Amphibia. The question 

 may become elucidated further by an adequate study of certain 

 irregularities which appear in the arrangement of the trigeminal 

 rami in Cryptobranchus (Fischer, '64; Wilder, '92; Mc- 

 Gregor, '96), Amphiuma and Siren (Wilder, '91, '92), and in 



