No. I.] THE CRANIAL NERVES OF AMPHIBIA. 145 



The outer division (p) soon subdivides (852 d=) into a lower or 

 ventral subdivision {go) composed of a portion of the fine fibres, 

 and an upper, or dorsal, and larger subdivision {g b) composed 

 of the remainder of the fine fibres and the mixed fibres. The 

 lower subdivision {p a) proceeds along the roof of the pharynx 

 a considerable distance, giving fibres to it and to some portions 

 of the filtering apparatus. It finally turns meso-ventrad, runs 

 inward along the floor of the pharynx and supplies the 

 epithelium of the roof of the gill cavity. This branch is ob- 

 viously similar to those described previously {6 b, etc.) as 

 innervating other portions of the pharynx. It is one of the 

 Rr. pharyjigei. 



The upper subdivision {gb) (852) proceeds cephalad and 

 ectad, supplying fibres to the M. levator arcus branchialis in 

 its vicinity, and comes to lie outside the outer angle of the 

 pharynx. At 654 it turns ventrad, passing through a thin 

 muscle lying in the body wall, and divides {gb^ and ()b^. 



Before this division occurs, the fibres in the upper subdivision 

 {g b) were so arranged that the mixed fibres occupied the outer 

 and the fine fibres the inner side of the nerve. When the 

 division takes place, however, the anterior, larger branch {g b^) 

 receives the fine fibres and also a bundle of coarse fibres (with 

 sheaths deeply stained), and the posterior branch {gb^ receives 

 mixed fibres. 



The anterior, larger branch {Qb^ proceeds cephalad and 

 ventrad along near the inner side of the body wall, i.e., around 

 outside the gill cavity. It then bends cephalad, and again 

 mesad, around under the gill cavity. During this part of its 

 course the coarse fibres are very plainly seen occupying its 

 ventral side. The fine fibres constitute the bulk of the nerve. 

 Finally, as the nerve proceeds mesad the majority of the coarse 

 fibres separate out (530 ±). As they separate out {gb^^ there 

 is a small group of ganglion cells apparently on the coarse- 

 fibred bundle. Some of the fibres of this branch innervate a 

 muscle which appears to correspond with Schulze's M. 

 ceratohyobranchialis. Other fibres seem to merely scatter in 

 the loose connective tissue and could not be traced. This 

 apparent peculiarity was observed in more than one specimen. 



