IV- OF RAXA PIPIEXS. 29 



the skull. A little in front of the globe of the eye it di\ides into two branches, 

 one of Avhich extends forwards as far as the vomerine bones (c), Avhere it gives fila- 

 ments to the internal nasal orifice, and to the neighborhood of the vomerine teeth ; 

 while the other, the larger, bends directly outwards (d), is situated behind the 

 palatine bones, till it reaches the inner surface of the upper jaw, where it forms a 

 distinct imion with the superior maxillary nerve, and after the union of the two 

 their terminal branches are distributed to the neighboring mucous surfaces. The 

 other collateral branches of the ophthalmic nerve are quite minute, one of which 

 is given to the upper eyelid and the skin in front of it, and two others perforate 

 the united frontals, and are distributed to the skin over the nasal cavities, and to 

 that of the nasal orifices. 



B. Upper Maxillary Branch. (Plate II. Figs. 2 and 3, e.) — This and the lower 

 maxillary branch ar-e so closely connected at their origin from the ganglion, that for 

 a short distance they appear to form but a single trunk, though with a little care 

 they may be completely separated. They become disjoined just behind the globe 

 of the eye, where the upper jaw" branch gives ofi" some minute filaments, which 

 pass between the muscles of the lower jaw, and are distributed to the sensitive 

 surface of the eye. A small branch is also given to the choanoid muscle, and 

 it is near this point that the ahducens leaves the trigeminus to reach the ex- 

 ternal rectus muscle. The terminal filaments, which may be regarded as identical 

 with the infra-orbitar nerve of the human body, are lost in the skin beneath and 

 in front of the globe of the eye. A collateral branch extends inwards beneath the 

 eye, and meets with the palatine, as already described, at d. 



C. Mandibular or Lotcer Jaw Branch. (Plate II. Figs. 2 and 3, /) — The third 

 principal trunk corresponds in its distribution with the same nerve in the higher 

 animals. Near its origin- branches are given to the muscles of the lower jaw, but 

 on reaching the angle of the jaw it passes over it to the outside ; then, descending 

 beneath, it runs parallel to it as far as the symphysis, where it breaks up into a 

 brush. Its collateral branches are distributed to the skin of the lower jaw and to 

 the mylo-hyoid muscle. 



D. Facialis (Portio dura). (Plate I. Fig. 1, a.) — The nerve in Frogs to which 

 this name has been given is quite different, in its mode of origin and of distribution, 

 from that to which the name has been given in the higher animals. The descrip- 

 tions of it by anatomists are far from coinciding with each other, and will be found 

 somewhat at vai'iance with that which foUow^s. 



In describing this nerve, Cuvier does not appear to speak from personal obser- 

 vation when he says, that " it is believed that a branch of the eighth pair (vagus) in 

 tailless Batrachians, as it goes towards the trigeminus, meets with a branch escaping 

 from the semilunar ganglion, and that the two united form the facial." * "Wagner, 

 in speaking of the cranial nerves in Frogs, says that the facial exhibits no distinct 

 roots, and is supplied as a branch of the acousticf Muller, referring to A'olkman, 

 remarks : " In Frogs Volkman has described a nerve analogous to the facial, which 



• Lemons d'Anat. Comp., 2me edit., Tom. III. p. 219. 



t Elem. Comp. Anat. Vcrtcb. Animals, New York, 1S45, p. 151. 



5 



