no NERVE COMPONENTS OF BONY FISHES. 



paleo-cranial (and hence visceral) motor rami of the vagus 

 (compare the discussion of Furbringer's theories in topic 

 V of Section 4). 



As a matter of fact it is probably quite impossible in 

 some cases to determine by dissection which of these 

 nerves supplies the pharyngo-claviculares or whether both 

 sometimes participate, as Vetter supposed. For example, 

 in Menidia the r. cervicalis of the first spinal nerve, as we 

 have seen, runs down immediately behind both of these 

 muscles and closely applied to their caudal surfaces along 

 their entire extent. The relations of this nerve to the in- 

 ternal muscle are especially intimate and while descending 

 along its caudal face several small cutaneous twigs are 

 given off which pass laterally along the surface of ihe 

 muscle on their way to the skin. These twigs are very 

 minute and their courses tortuous, and it is doubtful 

 whether even in a large fish they could be dissected out to 

 their terminations, though their whole courses can be 

 easily followed in the sections. It is probably these fibres 

 which Vetter supposed innervated the hinder part of the 

 muscle and he was mistaken in regarding them as motor, 

 but correct in his further supposition that, aside from 

 these fibres, a branch of the vagus which he had over- 

 looked furnishes the main innervation for these muscles. 



In the case of Menidia there is no room for doubt that 

 the relations are as above described. My sections are 

 perfect and absolutely free from ambiguity. Of course 

 it does not follow that the same conditions prevail in all 

 teleosts. If it is true that these muscles are innervated 

 from the first spinals in Amiurus (Wright) and in the 

 lower fishes (Flirbringer), this raises the question whether 

 the muscles so named are homologous in Menidia and 

 Amiurus and whether the pharyngo-claviculares of the 

 teleosts are homologous with the coraco-branchiales of 

 selachians and ganoids, as Flirbringer assumes to be the 

 case. 



An embryological examination may be necessary to 

 decide this matter, which is, however, of some theoretical 



