18 ATLAS OF BIOLOGY. 



FIG. VII. Ventral aspect of the same, after removal from the hody.* 



FIG. VIII. The same,- seen from the left side. 

 The origiu of the fourth cranial nerve is shown. 



FIG. IX. A dissection of the same from ahove, to show the ventricles. 



The lateral and optic ventricles have been exposed on the right side, and the median 

 portion of the cerebellum removed. On the left side the whole system of cavities has been 

 laid bare to the level of the foramen of Monro, in order to show the relationships existing 

 between the axial and lateral portions of the brain. 



FIG. X. The lateral and optic ventricles, exposed from the left side. 



FIG. XI. Vertical longitudinal section of the entire brain, cut a little to one side of 

 the middle line. 



Figs. VI. to XI. were drawn from brains preserved in alcohol. All x 3. 



The stippled surfaces represent cut edges. 



It is doubtful if the parts lettered ol. really represent the olfactory lobes, and the 

 morphology of the nervous tract connecting them has yet to be ascertained. It is also a 

 question if the body here termed pineal gland, p.gl., is the strict homologue of that of other 

 vertebrates. The latest researches in this direction are those of Osborne (1?A). 



FIG. XII. The right olfactory sac, opened up from without, along the line a, b of 

 Fig. XIII. 



The elevation in its floor overlies the vomer, and the forward growth from the lower lip 

 of the anterior nostril is supported by the aliuasal cartilage. (n.p. 1 Fig. VIII., PI. IV.) 

 x 4. 



FIGS. XIII., XIV., XV. Three figures of the eye-muscles and their nerves, the 

 nictitating membrane, and Harderian gland. All x 2j. 



XIII. Dorsal view. 



The whole integument covering the head was removed, and the superior-rectus of the 

 left side reflected. 



XIV. Ventral view. 



The mucous membrane of the roof of the mouth, and the levator-bulbi muscle of the 

 right side, were removed. A portion of the auditory capsule has also been dissected away,, 

 to expose the 6th nerve. 



XV. The same ; the inferior-oblique and recti muscles, and, on the left side, the outer 

 portion of the face, have all been removed. 



FIG. XVI. The eye, seen from without, in the living animal. 



FIG. XVII. Section of the left eye and eyelids, taken through the plane of the optic 

 nerve. 



* The pituitary body is not nnfreqnently produced into a pair of Literal expansions, thus becoming trilobed. 



