THE CRANIAL NERVES OF SCYLLIUM. 97 



the figures were drawn, with the camera, from individual sections and 

 the branches of the several nerves carefully filled in, again by the aid 

 of the camera, from other sections of the same series. In this way 

 such a view of the nerve is obtained as might be got from a transpa- 

 rent embryo in which the nerves alone stood out as opaque objects. 

 To prevent confusion, from the overlapping of different nerves, two 

 figures have been given, of which the first (fig. 11) shows the roots of 

 the fifth and seventh, the connections of these with one another and 

 with the third nerve, the branches of the latter and of the fifth, the 

 fourth nerve, and some of the branches of the seventh ; in the second 

 (fig. 12) the remaining branches of the seventh, with certain branches 

 of the glossopharyngeal are shown, and in addition to these, the whole 

 course of the ophthalmic branches of both fifth and seventh nerves. 

 The branches of the fifth nerve are seen to be the following : 



1. The ophthalmic branch (v a), which arises by a slightly ganglionic 

 root, runs forward over the obliquus superior (o.s.), crossing, as it 

 does so, the fourth nerve at right angles and giving off branches, some 

 of which appear to be connected with the fourth. 



2. The communicating branch (N.c.) between the Gasserian and 

 ciliary ganglia, the position and relations of which nerve are sufficiently 

 well shown in the figure. We reserve the discussion of this branch, 

 merely noticing here that, though we describe it with the fifth nerve, 

 it appears to belong to the third quite as much as to the latter. 



3. The main stem of the fifth, running down behind the first head 

 cavity (1) and the rectus extemus, receiving the communicating branch 

 (N.c'.) from the seventh, and after passing downwards and forwards 

 for some distance, dividing into two branches, (a) an anterior or 

 maxillary nerve (v b) which again gives off numerous branches to the 

 skin of the upper jaw; and (b) a posterior or mandibular (v c) which 

 runs backwards and downwards, lying in close contact with the outer 

 wall of the lower part of the mandibular head cavity (2) and supplying 

 it with branches. The distribution of ganglion cells is sufficiently 

 shown in the figure ; there is a small ganglion at the base of the 

 ophthalmic nerve, and the ganglion cells of the main stem extend 

 some little distance beyond the point of junction with the communi- 

 cating branch from the seventh. 



In figs. 14 and 15 some of these branches (v a, v b, v c) are seen at 

 a stage between o and p : except that the roots of v and vii are much 

 more closely approximated, thei*e is no difference of importance between 

 H 



