OF PIPA AMERICANA. 129 



ganglions of V and VII. My study of Pipa gives no indi- 

 cation of such a dual condition, since the nerve arises not 

 from the common ganglion of the V and VII, but as a 

 branch of the facial nerve. 



After the separation of the palatine, the main branch of the 

 facial (hy.man.y, turns outward and backward for some 

 distance, passing along a groove in the ventral side of the 

 otic capsule, between it and the roof of the mouth. Thence 

 it passes downward around the buccal cleft to the lower 

 jaw. After making this turn, the hyomandibularis runs 

 forward on the inner side of Meckel's cartilage along the 

 floor of the mouth. It soon gives off a branch (6wc.), 

 which in turn divides to innervate the mucous lining of the 

 mouth. This branch, although scarcely larger than several 

 that are given off later as terminal branches with similar 

 distribution, corresponds most nearly to the buccalis of 

 other forms. The main nerve continues its course forward 

 following the general contour of the jaw and is distributed 

 to the inner lining of the mouth. The chief points of in- 

 terest in connection with the facial in Pipa are the rela- 

 tions of the palatine and the apparent lack of connection 

 between the facial-glossopharyngeal commissure and the 

 facial proper. This of course is to be explained by the 

 peculiar relations of the VII to the V, the facial first appear- 

 ing as a distinct nerve coming from the trigeminal gang- 

 lion, the connection existing in the ganglion itself. 



The trigeminal nerve consists of three divisions arising 

 by as many separate roots from the anterior end of the 

 Gasserian ganglion. These three divisions will be de- 

 scribed in order corresponding to their origin from the 

 ganglion, namely, the mandibularis, the frontalis, and 

 the supramaxillaris superior. 



iHyo-mandibularis, Von Plessin = Jugularis, Fischer = Facial, Wyman. 



