(_b_) The optic nerve, arising from the ventral surface of the brain below the optic lobes, supplying the retina of the eye. (_c_) The trigeminal nerve, arising just behind the optic nerve, giving rise to the following branches:-- (_i_) The ophthalmic nerve, which passes over the muscles of the eye and supplies the skin in the region of the olfactory capsule. (_ii_) The maxillary nerve, which runs forward under the eyeball, and supplies the skin covering the upper jaw. (_iii_) The mandibular nerve, which is at first continuous with the maxillary, and then bends round the inner surface of the upper jaw to extend along the outer surface of the mandible. (_d_) The glossopharyngeal and the vagus (or pneumogastric) nerves, leaving the skull together, immediately behind the auditory capsule. The glossopharyngeal passes along in front of the hypoglossal nerve and proceeds along the base of the tongue. The vagus, after giving off branches to the dorsal muscles, reaches the walls of the pharynx and run obliquely backwards to supply the pharynx, heart, lungs and stomach. [Illustration: FIG. 18.--Brain. Cranial Nerves, Spinal Nerves, and Sympathetic Nervous System of Xenopus and Rana.] Make a complete sketch showing the brain and the above-mentioned cranial nerves. * * * * * Transcriber's Notes: Every effort has been made to replicate this text as faithfully as possible, including inconsistencies in formatting. Italic text is denoted by _underscores_ and bold text by =equal signs=. Both "exoccipitals" and "ex-occipitals" occur in original text, left as printed. End of the Project Gutenberg EBook of Dissection of the Platana and the Frog, by J. D. F. Gilchrist and C. von Bonde