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.