Herrick, Cranial Nerves of the Cod Fish. 309 



the others retained this function or became tactile organs, their 

 migration to the exposed surfaces of the body (barblets, fins, 

 etc.) is equally intelligible. 



It is greatly to be regretted that none of my series of sec- 

 tions is sufficiently perfect in the supra-temporal region to per- 

 mit me to state the exact distribution of the lateralis fibers 

 which go out Avith the r. lateralis accessorius. They all appear 

 to be given off with the earlier branches of this nerve, but, as 

 none of these branches could be traced to their ultimate ter- 

 mination, the small pit-organs to which these fibers are prob- 

 ably distributed could not be located. We have seen that all 

 of thp pit-organs found in the neighborhood of the supra-tem- 

 poral canal are supplied by the r. supra-temporalis vagi, while 

 the row extending back from this region to the dorsal fin is 

 supplied by twigs of lateralis fibers from the r. lateralis vagi. 

 This latter point agrees with the condition in Amia (Allis, '97) 

 and in Batrachus (Clapp, '99). 



The occurrence of lateralis fibers in the r. lateralis acces- 

 sorius of Gadus strengthens the possibility that the fibers which 

 I have described as arising from the base of this nerve to sup- 

 ply naked sense organs on the top of the head of Menidia may 

 be of the same nature. As I stated in my previous contribu- 

 tion, the innervation of these organs in Menidia is not abso- 

 lutely clear, as I was not able to exclude the possibility that 

 lateralis fibers go out with the facial root of the r. lateralis ac- 

 cessorius. The matter is fortunately not one of great morpho- 

 logical importance, as the occurrence of both types of fibers in 

 any form will simplify the interpretation of other cases in which 

 either or both components may be present. 



Thus, the communis component alone may be present as 

 in siluroids, and as in Petromyzon possibly, if Cole's sug- 

 gestion ('98 a) holds good. On the other hand, the reduc- 

 tion of the communis element and the exaggeration of the lat- 

 eralis element might lead to such a condition as that described 

 for Batrachus by Miss Clapp ('99). Here the r. lateralis acces- 

 sorius evidently receives from its facial root a large number of 

 lateralis fibers which are distributed to lateral line organs in a 



