CoGHir.L, Cranial Nerves of Ainblystoma. 265 



group, but because of its relation to the mouth would homolo- 

 gize it also with the post-trematic nerves." Elsewhere in the 

 same contribution it is stated that "the inner row of mandib- 

 ular sense organs at the margin of the lower lip is innervated by 

 the hyomandibularis (mandibularis internus)." Platt, there- 

 fore, considers the r. mandibularis internus as a post-trematic 

 nerve innervating lateral line sense organs. This author be- 

 lieves that these organs are in part innervated by the general 

 cutaneous system ; but the r. mandibularis internus is not even 

 general cutaneous but communis in function. Moreover, lateral 

 line nerves cannot be classed in the branchial system as Strong, 

 Herrick and others have conclusively established. The nerve 

 which Platt has thus interpreted in Necturus as the mandibu- 

 laris internus is in all probability the mentalis internus accord- 

 ing to Druner's report upon Menobranchus, and on account 

 of its function should be distinguished sharply from the bran- 

 chial rami of the hyomandibular trunk. 



Strong interprets the r. mandibularis of fishes, and of 

 Anura, the r. alveolaris of Urodela and the mammalian chorda 

 tympani as homologous structures. Bowers adopts Strong's 

 interpretation for Spelerpes. Cole ('96, p. 660) considers the 

 r. mandibularis of Anura as a pre-trematic nerve fused with the 

 post-trematic, an hypothesis based upon his view that the 

 typical post-trematic nerve is motor only. Druner looks upon 

 the r. alveolaris as a pre-spiracular nerve but denies that it is 

 the homologue of the chorda tympani, since he accepts 

 Froriep's idea that the chorda tympani is a post-spiracular 

 nerve. Druner claims, further, that the r. jugularis cannot be 

 considered as belonging to the post-trematic VII. These con- 

 flicting opinions of recent authors show that the morphology of 

 the branchial rami of the facialis in Amphibia is in a most 

 unsatisfactory state. It is the purpose of the following para- 

 graphs to emphasize a number of important f icts which have 

 not been properly recognized in their bearing upon this 

 question. 



My interpretation of these rami may be stated as follows: 

 "I. The r. alveolaris VII is a pre-spiracular nerve and as 



