RAMUS PRE-TREMATICUS FACIALIS. I 73 



V. — The Ramus Pre-trematicus Facialis. 



A large bundle of communis fibres runs from the ventral 

 surface of the geniculate ganglion, enters the same fora- 

 men as the truncus hyomandibularis, crosses the latter 

 nerve and gives to it a considerable communis component, 

 as already described. Immediately after its emergence 

 from the cranium it divides into two approximately equal 

 portions; one, the r. palatinus, passes cephalad along the 

 cranial wall under the origin of the m. adductor arcus 

 palatini, the other (to which I have applied the name r. 

 pre-trematicus VII, r. VII . p. t.) turns directly ventrad 

 along the caudal and inner face of that muscle and between 

 it and the large pseudobranch, whose cephalic end is 

 crowded far dorsad (Fig 2). This nerve is chiefly distrib- 

 uted to the mucosa of the roof of the mouth and its con- 

 tained taste buds cephalad of this point ; but several large 

 branches run caudad along the anterior surface of the 

 pseudobranch and between its lobes. Having reached its 

 caudal and ventral surfaces, they spread out and doubtless 

 supply the numerous taste buds of the underlying mucosa 

 and also the pseudobranch itself. Though these fibres on 

 account of their extreme tenuity and delicate myelination 

 could not be traced into the substance of the pseudo- 

 branch, yet there can be no doubt that they do innervate 

 this organ, as they spread freely over its surfaces, and 

 besides the pseudobranch receives no nerve supply from 

 any other source. 



The morphology of the teleostean pseudobranch, in 

 spite of several recent papers, is in a very unsatisfactory 

 state, and yet it is of great importance for the proper 

 interpretation of all of the branches of the facial nerve. 



Stannius states that it is usually in the teleosts inner- 

 vated from the IX nerve, and cites the following cases; 



