BOWERS. — CRANIAL NERVES OF SPELERPES BILINEATUS. 183 



(3) coarse fibres from the roof of the mesencephalon (not shown in the 

 Figures), which curve ventrad and caudad and pass out of the brain 

 with the other roots of the fifth. After emergence from the brain, the 

 trigeminal fibres run obliquely cephalad and laterad, as indicated in 

 Figures 1 and 2 (PL 1), and can be traced through the ventral half of 

 the Gasserian ganglion into rami ophthalmicus, maxillaris, and man- 

 dibularis. The fibres are of medium size and in iron haematoxylin take 

 a grayish blue stain, in sharp contrast to the large fibres from the seventh 

 nerve, which take a deep blue stain. The latter run through the dorsal 

 part of the ganglion, from which they emerge as r. ophthalmicus super- 

 ficialis VII. and r. buocalis VII. 



(2) Branches. — (a) Ramus ophthalmicus trigemini (Figs. 1-4, V. 

 opt.) leaves the anterior mesial part of the Gasserian ganglion, runs 

 directly cephalad, and comes in contact with III. and VI., as already 

 (pp. 181 and 182) described. Just posterior to the eye, in the transverse 

 plane in which the optic nerve emerges from the cartilage of the brain 

 wall, the ophthalmicus trigemiui gives off a large dorsal branch ( Va, 

 Figs. 1, 3, 4). From this branch arise two small branches Va 1 and 

 Va 2 (Fig. 3). The more posterior and lateral of the two branches 

 ( Va 1 ) follows m. rectus superior to its insertion on the eyeball. 



The other branch ( Va 2 ) goes to the skin of the dorsum ; it divides, 

 sending one branch cephalad and another caudad. The main branch 

 ( Va) curves along the dorsal median surface of the eye (Figs. 1, 3, 4) 

 in connection with IV. (Fig. 4), as previously described, and is dis- 

 tributed to the skin in the region in front of the eye. 



Ramus opthalmicus V., after giving off the dorsal branch ( Fa) just 

 described, takes its* usual course forward, above the optic nerve (Fig. 3), 

 close beside m. rectus internus, and divides into three branches (Figs. 

 1-3). The most ventral of these ( V. I. na.) curves around in front of 

 the eye to the skin of the external nares and cheek ; it corresponds to 

 Gaupp's r. lateralis narium. The middle one of the three branches curves 

 ventrad and anastomoses (corns.) with r. palatums VII. This condition 

 agrees with that found by Herrick in Amblystoma. Strong ('95, p. 122) 

 also finds an anastomosis of these two branches in the tadpole, but it takes 

 place farther cephalad than in Spelerpes. The anastomosing nerves 

 continue cephalad after their union, but could be traced only a short 

 distance in the loose tissue in the roof of the oral cavity, just median to 

 the internal nares. The most dorsal of the three branches ( V. m. na.) of 

 the ophthalmicus (Gaupp's r. medialis narium) runs above the olfactory 

 and innervates the skin at the tip of the nose. 



