This work was commenced at the suggestion of Prof. Ewart, F.R.S., to whose kindness I am indebted for the material used, and for much assistance and advice during the progress of the investigation. Prof. Ewart placed two specimens at my disposal—a male and a female, both of which were about 43 cm. long, excluding, of course, the lash. As, however, the male had been partly dissected for special points in connection with another investigation, it was only available for the study of the IXth and Xth cranial nerves; the main bulk of the present work, therefore, having been carried out on a single specimen. Hence there are several points on which my work will require confirmation.
As the dissection of the cranial nerves of Chimæra elucidated facts of a more interesting character than I had anticipated, it was thought desirable to publish a preliminary statement containing a brief account of the facts, and to leave the full description with figures and morphological deductions for a future communication, which I hope to lay before the Eoyal Society in a few weeks' time. The present paper, therefore, pretends to be a brief review of the more important facts and nothing more.
Having nothing new to describe with respect to the olfactory and optic nerves, I shall commence with the oculo-motor:—
Third Nerve.—This is a large nerve, and arises from the crus cerebri by two principal roots just behind the pituitary body. On emerging from its foramen in the orbit, it immediately gives off a branch to the superior rectus muscle of the eye, and divides into two large dorsal and ventral branches running respectively over and under the optic nerve.