No. I.] THE CRANIAL NERVES OF AMPHIBIA. 117 



The main nerve, proceeding further ectad, soon gives off 

 another twig of several fibres (^ VII b^^,, 727). This twig imme- 

 diately fuses with a fine-fibred twig, also very minute, which is 

 given off by the largest and outermost of the accessory tri- 

 geminal branches described above (p. 17) as issuing from the 

 anterior extremity of the Gasserian ganglion. These two 

 bundles of fibres thus brought together are distinguishable 

 from each other, owing to their difference in fibre calibre, and 

 soon separate, the trigeminal portion going caudad and dorsad, 

 and coming in contact temporarily with a division of the middle 

 of the accessory trigeminal twigs just above the outer edge of 

 the auditory capsule. The facial portion proceeds ectad and 

 has a distribution near and probably similar to the preceding 

 facial twig, though it could not be so clearly traced. 

 . The main nerve (^ VII b^ continuing ectad comes in contact 

 (726) with the outer of the accessory trigeminal branches. 

 This contact and temporary fusion is a peculiar one : the facial 

 passes through the trigeminal branch, each, however, seeming 

 to preserve its continuity. At this point of contact each gives 

 off a twig. That from the trigeminal portion is fine-fibred, 

 and fuses — temporarily, apparently — with the facial twig 

 (}^ VII b^^. The fibres of these very minute trigeminal twigs 

 are so fine that it is not possible to ascertain in ordinary prep- 

 arations whether some fibres may not remain with the facial 

 twigs. The main trigeminal branch now breaks up, and sup- 

 plies the skin of the region just ectad of the posterior surface 

 of the eyeball. The facial twig (^ VII b^^ divides. One part 

 crosses and temporarily fuses with a trigeminal twig {^oo-6%'j)y 

 proceeding cephalad parallel with the principal facial branch. 

 Some of its fibres are traceable to a large lateral line sense- 

 organ in the epidermis, just below the cornea (625). The 

 remaining four fibres proceed further cephalad and innervate 

 a lateral line sense-organ cephalad of the latter and in a 

 similar position (588). The other part of this facial twig could 

 not be completely traced to lateral line sense-organs. 



The main branch (5^ VII b^, after giving off these twigs, 

 bends forwards, proceeding cephalad under the eye. At intervals 

 it gives off small twigs of only a few fibres each. Many of these 



