54 Journal of Comparative Neurology. 



the papillae which are so .numerous on the dorsal fin, and which 

 probably correspond to the structures innervated by the R. lat- 

 eralis trigemini. The R. branchialis would probably represent 

 the R. lateralis. I am forced to believe that the exact anatomy 

 of these nerves is not yet accurately known, nor have their 

 connections with the cutaneous sense organs been sufficiently 

 worked out." It is evident that Strong has been misled here 

 by the imperfect description of the roots by Ahlborn. Not 

 one of the considerations stated holds good when it is known 

 that this nerve, including the recurrent branch from VII, does 

 arise from the acusticum, that the pits on the sides and 

 ventral surface of the gill region are innervated by other rami 

 containing lateral line components, and that this nerve- is prob- 

 ably destined for lateral line organs caudal to the gill region. 



Following Strong, but independently. Cole ('98, p. 179) 

 comes to the same conclusion from the work of Stannius, Ahl- 

 born, and Ransom and Thompson ('86). Cole says: "It seems to 

 me therefore that there is room for little doubt as to the morpho- 

 logical value of the ' lateralis ' nerve of Petromyzon, since all the 

 known facts of its anatomy point to the conclusion that it be- 

 longs to the accessory lateral series. First, we know that its 

 roots correspond to those of the accessory lateral system in 

 higher Teleosts, and that besides its posterior or vagal rootlets, 

 it has also an anterior or (trigemino— ?) facial root ; second, its 

 fibers are of the same nature, being somatic sensory in function ; 

 and third, it is connected with the spinal nerves in a manner 

 characteristic of the accessory lateral series, and such as to jus- 

 tify Ransom and Thompson's description of it as a commissural 

 nerve. " The only point of any significance here, besides those ad- 

 duced by Strong, is the connection with spinal nerves de- 

 scribed by Ransom and Thompson. These authors, according 

 to Cole, also state that the lateralis nerve has no ganglion. It 

 must be said that if they were unable to find the ganglion, 

 which constitutes more than two-thirds of the whole ganglionic 

 complex of the vagus group, their evidence with regard to con- 

 nections may be considered as of doubtful value until confirmed. 

 C. J. HERRfCK ('00, p. 309) views the suggestion of 



