The fibers of the portio minor do not take part in the formation of the Gasserian ganglion, but are only partly surrounded by it. There are three nerve trunks given off of the trifacialis: the ophthalmic, the superior maxillary, and the inferior maxillary. The _ophthalmic division_ of the fifth nerve is the smallest of the three branches. It emerges directly from the Gasserian ganglion, and passes through a narrow bony canal in the base of the brain, below the pathetic and the abducens, and through the foramen ophthalmicum. It then enters the eye cavity above the optic nerve, and on the wall of the cavity extends downward, and with regard to the eyeball, dorsally lying close to the rectus internus muscle and close to the surface of the eyeball. It passes along the olfactory nerve, extends under the superior oblique muscle, and finally reaches the inner angle, or canthus, of the eye. It here divides into the recurrent externa and the ethmoidalis. The ethmoidalis branch is a straight continuation of the ophthalmic. It extends along close to its fellow of the opposite side, and, over the vomer, splits into two branches. The smaller of these branches breaks through the bone cells of the jaw, continues upon its ventral surface in a furrow extending forward, and terminates in the gum region. It supplies the gum and point of the beak. The larger branch enters into the cell substance extending to the tip of the beak, in its course sending out a number of fine filaments, which spread out along the outer surface. At this point these two branches may fuse. The larger branch is endowed with the sense of touch. The recurrent externa divides shortly after leaving the main trunk of the eye cavity passes over the lacrimal gland. It gives two branches to this gland and one to the membrana nictitans, and innervates the upper eyelid. It then emerges from the eye cavity, passing over the os lacrimale, and gives one or more branches to the integument of this region, including the comb. This branch is large in birds with a large comb. Branches pass in front of the lacrimal bone through the outer nasal cavity and into its deeper structure. Shortly after the ophthalmic branch has entered into the eye cavity and before it crosses the optic nerve, it gives a fine branch to the motor occuli. The second and the third branches of the fifth cranial nerve are mixed. They contain elements of both the portio major and the portio minor. These two branches come from the lower part of the outer region of the ganglion, and pass together through a cavity which is located between the os petrosum and alæ and basis sphenoid, and then branch.