THE INFRA-ORBITAL TRUNK. 185 



VII. Their nerve fibres, like those of the opercular 

 organs just referred to, are of medium or small size. 

 That these organs are morphologically equivalent to those 

 on the operculum, I think is clear. They therefore proba- 

 bly belong- to the lateral line system. Whether they de- 

 rive their fibres from the r. mandibularis V or from the 

 r. mandibularis VII, I cannot determine with absolute 

 certainty by direct observation. I think undoubtedly 

 from the latter, for, on the one hand, the r. mandibularis 

 V contains no other lateralis fibres, while, on the other 

 hand, all of the similar naked opercular organs are sup- 

 plied by the facialis. Moreover, it can be definitely de- 

 termined that the anastomosing branch 8 between the r. 

 mandibularis V and the r. mandibularis VII contains 

 fibres from both the V and VII nerves. Inasmuch as 

 these fibres are all rather fine, those from the VII cannot 

 be separately followed in Weigert preparations. In the 

 osmic acid preparations, however, the analysis of the VII 

 and V fibres in this nerve can easily be made, as the VII 

 fibres, though no larger than the largest cutaneous fibres 

 from V, yet take the metallic impregnation much more in- 

 tensely. It can here be easily seen that the V fibres all, or 

 nearly all, are given off from the recurrent nerve before it 

 reaches the mandibularis VII, while the fibres, from the 

 latter can be separately traced cephalad after the anasto- 

 mosis with the V into the branch which supplies the three 

 mandibular organs in question. As the skin of this region 

 was not perfectly preserved in these sections, it was im- 

 possible to trace these darker fibres into their organs. 

 There is, in my mind, no doubt that the relations 

 expressed in the plots are correct. 



Immediately after the separation of the third branch of 

 the r. mandibularis V, a minute twig (the 15th infra- 



