626 
cavity, and it is said, in the index lettering, to be the “foramen for 
the 1st. and 2nd. rami of nervus trigeminus.” Posterior to this recess, 
or so-called foramen, there is another and smaller one which is said 
to be the “foramen for 3rd. ramus of nervus trigeminus and part of 
nervus acusticus.” This latter foramen lies near the anterior edge of 
what is said to be a membrane that closes the labyrinth cavity, and 
this membrane is said to be perforated by the nervus acusticus, but 
no perforation of it other than the one above mentioned is shown. 
On either side of the sloping dorsal portion of the postorbital portion 
of the chondrocranium two foramina are shown which are said to 
be “for the 1st. and 2nd. rami of nervus trigeminus”; and on the 
ventral surface of the postorbital portion of the chondrocranium, 
posterior to the so-called tympanic pedicle, several foramina are shown, 
one of which is said to be the “foramen for 3rd. ramus of nervus. 
trigeminus” and another the foramen for the carotis posterior. 
Huxuey says of the chondrocranium of this fish that it is “ prod- 
uced inferiorly and laterally into two stout suspensorial or palato- 
quadrate processes, with the pulley-like ventral ends of which the 
strong Meckelian cartilages are articulated.” The cranial cavity is not 
described by him, but he gives a median sectional view of the skull 
which shows the pituitary fossa with sharply developed anterior and 
posterior walls, the latter slightly overhanging the hind end of the 
fossa. The canals traversed by the trigeminus and facialis nerves are 
shown in a horizontal sectional view of the chondrocranium, the 
facialis nerve of this figure being the so-called 3rd. ramus of nervus 
trigeminus of GÜnTHER’s descriptions and figures. 
Van WuHE gives a diagrammatic figure showing the external 
openings of the canals traversed by the nerves, arteries and veins of 
the region, while Krawerz gives a median sectional view of the chon- 
drocranium which shows nothing of the region here under considera- 
tion excepting only a pituitary fossa similar to that shown by Hux.ey.. 
These several descriptions of the adult are readily seen to be 
wholly inadequate in so far as the region here under consideration 
is concerned, the only facts of importance that are disclosed being 
that the pituitary fossa is strictly of the selachian type, that there is. 
no indication whatever of a myodome either in process of formation. 
or of reduction, and that the nerves, arteries and veins of the region 
have apparently been so enveloped by the largely developed cartilage 
that they traverse wholly separate and independent canals. 
