_post-branchial_ branch (visceral motor) similarly related to the hinder margin. {380}[Illustration: FIG. 218.—Diagram showing the principal branches of the cranial nerves in a Fish, _mk.c_, Meckel's cartilage; _ol.o_, olfactory organ; _p.q_, palato-quadrate; _s_, spiracle; i-v, branchial clefts; i, ii, iii, iv, vi, the first, second, third, fourth, and sixth cranial nerves. The remaining nerves are differently shaded. _Black_.—The trigeminal nerve: _g.g_, Gasserian ganglion; _md_, mandibularis; _mx_, maxillaris; _op.p_, ophthalmicus profundus. _Oblique shading_.—The lateralis system and its centre (_t.a_), the tuber acusticum: _bucc_.vii, buccalis branch of vii; _md.ex_, external mandibular branches of vii; _l.n._x, lateralis nerve, with its supra-temporal branch (_s.t_), and its commissural connexion (_c_) with _op.s._vii, the ophthalmicus superficialis of vii; viii, auditory nerve. _Dotted_.—The facialis proper, including _c.t_, chorda tympani; _gn.g_, geniculate ganglion; _hy_, hyomandibularis, with its motor branches _m_, _m_, _m_; _p.n._vii., palatine. _Dark grey_.—The glossopharyngeal (ix), with its pre- and post-branchial branches and its palatine nerve, _p.n._ix; anastomosing with the palatine branch of vii (Jacobson's anastomosis). _White_.—The vagus: x^{1-4}, the branchial nerves, ganglionated and forking over clefts ii-v; _v.n._x, visceral nerve; _oc_, occipito-spinal nerves; _d.r_ and _v.r_, the dorsal and ventral roots of the first two spinal nerves. (Slightly modified after Wiedersheim.)]