Section 127. If the Student Will Now Recur to the Figures of the Dog's

skull (Sheet 6), he will see certain apertures indicated in the cranial wall. Of these, o.f. is the optic foramen for the exit of nerve II., perforating the orbito-sphenoid. Behind this there comes an irregular aperture, (f.l.a.), the foramen lacerum anterius, giving exit to III., IV., VI., and V1. V2 emerges from the foramen rotundum, and V3 from the foramen ovale, two apertures uniting behind a bony screen.* Just in front of the bulla is a foramen lacerum medium (f.l.M.), through which no nerve passes.

* In the rabbit's skull f.l. anterius, the foramen rotundum, and foramen ovale are not distinct, and there are two condylar foramina instead of one, through each of which, a moiety of XII. passes.