— 87 — 



oticus canal in the sphenotic, issue on the dorsal surface of tlie skull beneath the frontal bone. A 

 lateralis branch is then sent to the infraorbital organ in the postfrontal, and a second branch to the 

 organ in the pterotic, these two branches apparently containing all the lateralis fibers of the nerve. 

 The remainder of the nerve then runs backward beneath the dermal bones of the top of the skull, 

 enters the temporal fossa and there runs into and anastomoses with the supratemporal branch of the 

 vagus, branches being sent backward, from the united nerves, along the dorsal surface of the trunk. 

 As the main nerve passes dorso-mesial to the dilatator groove, it lies very close to that groove, and 

 may even be exposed in the bottom of it. A venous vessel, a branch of the external jugular, here 

 perforates the bottom of the groove and joins the nerve, accompanying it in its further course toward 

 the bind end of the skull. 



In Lepidotrigla the ramus oticus is a purely lateralis nerve, and is not continued posteriori^ 

 beyond the second organ in the pterotic, the pterotic in this fish lodging two organs innervated 

 by the oticus, without an intervening primary tube. This condition of these two organs in this fish 

 would seem to represent a stage in the reduction of the two organs here found normally developed 

 in Amia and certain other fishes to the one organ found in Scorpaena and still other fishes; a reduction 

 strictly similar to that that is taking place in the 4 th. and 5 th. supraorbital organs both of Lepido- 

 trigla and of Scorpaena. In Lepidotrigla, the general cutaneous and communis fibers that accom- 

 pany the oticus in Scorpaena are represented (or replaced) by fibers that do not traverse the oticus 

 canal; and this is also the condition in Amia, in which fish the ramus oticus is also a purely lateralis 

 nerve while the ophthalmicus lateralis branch that supplies the anterior head line of pit organs is 

 accompanied by fibers the character of which was not determined in my work on that fish, but which 

 have an apparent origin and distribution similar to that of the fibers that accompany the oticus in 

 Scorpaena. 



In Dactylopterus the oticus lateralis is accompanied by a bündle of general cutaneous fibers, 

 and apparently by those fibers only. 



In Ameiurus, the ramus oticus is said by Herrick ('Ol) to contain lateralis, general cutaneous, 

 and communis fibers, to have an intracranial origin, and, running upward, to pierce the roof of the 

 skull; which would seem to mean that it does not first issue in the bind end of the orbit before 

 entering and traversing the oticus canal. In Menidia the ramus oticus is said by Herrick ('99) to 

 contain lateralis and general cutaneous fibers, and to correspond to the ramus oticus plus the external 

 buccal of Cole's descriptions of Gadus : that is, its lateralis fibers innervate not only the latero-sensory 

 organs in the postfrontal and pterotic sections of the main infraorbital canal but also the organ 

 in the dorsal postorbital bone. The ramus oticus of Menidia, minus the external buccal portion, is said 

 to traverse a canal in the sphenotic and, as just above stated, it contains both lateralis and general 

 cutaneous fibers. This intimate association, in this nerve, of fibers that are considered by the author to 

 have a central origin in the facialis and trigeminus segments, respectively, leads Herrick to conclude 

 that the oticus ,,was probably originally the dorsal ramus of the facial nerve to which lateralis ele- 

 ments have been secondarily added and whose general cutaneous portion has, like that of the pro- 

 fundus nerve, been cenogenetically fused with the Gasserian ganglion". That is, it is assumed, in 

 this Statement, that general cutaneous fibers that originally issued from the brain by three distinctly 

 different apparent roots, and that belonged to three distinctly different but adjacent metameric 

 Segments, have come, in Menidia, to issue by a single apparent root and from a single, unsegmented 

 cerebral center; this being the result of a central condensation so complete that all traces of the ori- 



