No. I.] THE CRANIAL NERVES OF AMPHIBIA. 1 65 



relinquished by the dorsal VII is taken up by the VIII. The 

 dorsal VII completely disappears in adult Anura, and the inter- 

 esting question arises: Does the dorsal VII really atrophy, or 

 does it merely pass over into the VIII } This part of the VII 

 is much more distinct from the VIII in Urodela than in the 

 tadpole. In the former it has a distinctly separate exit ; in the 

 latter it and the VIII emerge from the medulla together, the 

 dorsal VII soon separating, apparently as a branch from the 

 VIII. It is certain that when the dorsal VII has disappeared 

 its place is completely occupied by the VIII. The question, 

 however, as to whether there is an extinction or a transference 

 of the dorsal VII can only be answered by following the 

 central terminations of the two nerves on through to the final 

 disappearance of the dorsal VII. 



This disappearance of the lateral line component of the VII 

 probably invalidates homologies which have been advanced 

 between its branches in lower forms and its supposed repre- 

 sentatives in higher. One of these homologies (R. auricularis) 

 has already been noticed, and another will be discussed 

 below. 



In connection with the question here raised arises the inter- 

 esting problem of the relation of the auditory organ to the 

 lateral line system. The idea that the auditory organ is 

 connected genetically with this system, advanced by Mayser 

 and later by Beard and developed so ably by Ayers, seems 

 likely to find general acceptance. It is not intended to enter 

 into this question in this paper, but it may be remarked that a 

 general survey of the facts of the innervation of these two 

 organs certainly points strongly to a close connection between 

 them. 



Incidentally, another point may here be mentioned about 

 which there seems to have been some confusion and which 

 here receives its solution. Osborn says (45, p. 66): "It is 

 seen that, whatever may prove to be the peripheral distribution 

 of the fibres of the fasciculus communis and posterior longi- 

 tudinal fasciculus, whether to the 7th or 8th, two facts remain: 

 first that the 8th arises ventral to the 7th, although a purely 

 sensory nerve." In a footnote he states that Dr. E. C. Spitzka 



