366 H. W. NORMS AND SALLY P. HUGHES 



3. The ramus supratemporalis X 



This nerve is exclusively lateralis in composition. It leaves 

 the ventrolateral border of the anterior division of the lateral- 

 line ganglion, and after running posteriorly for some distance in 

 the vagal canal passes out dorsolaterally through a small canal 

 in the posterior wall of the ear capsule (figs. 41 and 42, spt. X). 

 It divides within the canal, an anterior branch passing dorsally 

 and anteriorly along the dorsolateral border of the ear capsule 

 and finally to the periphery to supply the sense-organs of the 

 commissural canal and the two pit-organs situated just anterior 

 to the external opening of the endolymphatic duct (fig. 50, 

 spt. X). A posterior branch passing dorsally and posteriorly 

 supplies ramuli to the neuromasts of the main lateral-line canal 

 immediately following those supplied by the ramus supra- 

 temporalis IX. In the specimen used in the plotting of figure 

 51 there are six of these ramuli supplied to the main cana 1 ; in a 

 second specimen only four. 



4- The ramus dor salts X 



The term ramus dorsalis is here used as a non-committal 

 designation of a ramus exclusively lateralis in composition, that 

 arises from the second of the three divisions of the lateral-line 

 ganglionic mass of the vagus, and is distributed in part to neuro- 

 masts in the main lateral-line canal, but mostly to pit-organs 

 in the occipital and dorsal anterior trunk regions. It evidently 

 comprises a number of nerves, which, however, have a com- 

 mon origin from the ganglion and a similar distribution. There 

 emerge from the ventrolateral border of the ganglion three bands 

 of fibers. The two anterior may unite loosely into a common 

 nerve, the third runs almost directly posteriorly and soon sepa- 

 rates from the other two, rejoining them only through anasto- 

 moses. A large tract of one of the anterior bands may rejoin 

 the main lateral-line nerve. There is a tendency in the origin 

 of all of them for small tracts of fibers from the ganglion to join 

 the larger ones some distance from the origins of the latter, 

 forming in this manner a kind of plexus. A single nerve finally 



