596 GEOLOGICAL SURVEY OF THE TERRITORIES. 
nerves and the internal jugular vein. The lateral terminations of 
the occipital, the paroccipital processes, are large, thin, pointed for- 
wards, and on a lower level than the rest of the bone, forming a 
large part of the floor of the tympanic cavity. The semi-elliptical 
contour of the cranium, regarding it from a basal view, is well car- 
ried out laterally by the wing-light and attenuated mastoids. They 
contribute largely to the formation of the walls of the tympanic 
cavity internally, and externally assist in some degree towards com- 
pleting the temporal fosse. These fosse are deep; commencing 
posteriorly on either side at the external borders of the depressions 
already mentioned that bound the cerebellar prominence laterally, they 
take a course upwards and outwards, terminating at a foramen that lies - 
just within the pesterior periphery or the orbit, which foramen allows 
the passage of the tendon of the temporal muscle. From the upper 
boundary of the temporal fossz to where the frontals suddenly abut 
against and even overhang, to some extent, the nasals, the external and 
superior surface of the skull is of a pearly whiteness and very smooth in 
the dry skeleton, presenting not a trace of the sutures between the bones 
that go to form it, the frontals and parietals. This surface is divided 
by a well-marked furrow, that extends in the median line between the 
cerebellar prominence and the upper mandible. It is deepest in the 
parietal region. Close inspection of this area reveals minute ramifying 
grooves for the lodgment of vessels, one set running in the direction of 
the temporal fosse and another toward the orbits. In the “ bird of the 
year” the skull-cap is very thin and brittle in the dry condition; but a 
very different state of affairs presents itself when we remove a section 
of the cranial vault from above, in the adult, where the skeleton is full- 
grown, such as we have before us. We find exposed to our view one of 
the common characteristics of the family ; the two tables are light, thin, 
but compact, with a goodly supply of diploic tissue between them, at- 
taining a thickness in some localities, notably above the exit of the olfac- 
tories, of two millimetres or more. Owing to the large orbital cavities, 
the brain-case is crowded to the rear to such an extent that the fossz 
for the cerebral hemispheres are situated immediately over the cavities 
intended for the other encephalic lobes. We find the internal opening 
of the foramina, already described, at the base of the brain. The petro- 
sals have the appearance of two white leaves, harder than the surround- 
ing bone, slightly turned upon themselves, with their stems leading 
towards the fossa for the hypophysis. They present for examination the 
openings for the portio dura and portio mollis, the former foramen being 
on a lower level and anterior to the latter. In the median line running 
from the cerebellar fossa to the exit of the first pair of nerves along the 
roof is a raised crest, grooved on its summit for the longitudinal sinus. 
It sinks for a little distance, in the fresh specimen, into the cerebral in- 
terspace. The ‘sella turcica” is deep, its long axis being perpendicular 
to a plane passing through the foramen magnum. It hasatits base the 
openings for the carotids. Immediately beyond its anterior superior bor- 
der is seen the optic groove, with its foramen at either end, for the passage 
of the optic nerves and lodg ment for the optic chiasma. Above the optic 
foramina, situated stiil more anteriorly,is a conical pocket, pointing for- 
wards and a little upwards, with the olfactory foramina at its apex, two in 
number, giving passage for tlie nerves to the orbits. The basi- sphenoid i is 
thoroughly united with all the bones it comes in contact with, except the 
pterygoids, palatines, and tympanics. Its anterior process—the basi- 
presphenoid—loses itself in the interorbital septem, not a trace re- 
maining of the original margins of the two bones. Its wings, the orbito- 
