1G6 
MR. W. K. PARKER ON THE STRUCTURE AND 
on their inner face by the anterior paired vomers, which are very slightly separated 
from the palatine processes of the premaxillaries (p.px.) ; the whole of these bony 
tracts has been figured here, in situ. In the dilated front end of the lower opening 
the inferior turbinals ( i.tb.) are seen, and the folds of the middle turbinal ( m.tb.) in 
the hinder rounded space. Where the floor turns inwards and upwards towards the 
septum (p.e., s.n.), there it gives off a spike of cartilage which nearly reaches the 
recurrent lobe; this spike is the precurrent cartilage. The line of junction of 
the proper cranium with the nasal labyrinth (o.s., al.e.) is quite visible ; the orbito- 
sphenoidal region of the cranial w T all and roof is very wide, and has a convex outer 
face. The stem of each tract is narrow, and becomes, after ossification, the permanent, 
small orbitosphenoid. Each band winds round behind the corresponding lobe of 
nasal labyrinth, and is not flush with it, below ; the two bands are continuous with 
the presphenoidal region of the prepituitary basal beam. 
That beam is thickest where these bands join it; it is mainly formed of the inter- 
trabecula, for the paired trabeculae are flattened against the median part, and then 
cease between the hinder part of the right and left nasal floors. The chink between 
the convex hinder edge of the orbitosphenoidal stem (o.s.) and the concave edge of 
the alisphenoidal lobe (al.s.) is ear-shaped and curves backwards, and is large and 
round against the basal beam ; this is the large sphenoidal fissure for the ophthalmic 
and orbital nerves (V 1 .). The small optic foramen is oblique, and is hidden in this 
view by the aiisphenoid (see fig. 3, II.). The basal cartilage is very narrow between 
the orbito- and alisphenoids, and then expands suddenly, to remain wide to the end 
of the skull. Here, as in all typical Insectivores, the basis cranii in the early skull 
is extremely wide, ready to become pneumatic in relation to the auditory function. 
Even where the large cochlese (clil.) push their coils right and left against the basi- 
sphenoidal, at its junction with the basioccipital, region, it is still nearly four times 
as broad as at the point where the presphenoid and basisphenoid meet. 
The stem of each aiisphenoid scarcely becomes pinched in, but its margins are both 
concave, having the emerging orbital nerves in front of it and the swelling cochlea 
behind. Just where the latter concavity is seen, there the sub-basal cartilage swells 
out into a mammillate mass, which looks outwards and forwards, reaching three- 
fourths of the distance to the sphenoidal fissure. These solid masses, which look like 
the basipterygoids of a Lizard or Bird, are the chondrocrania] form of the “ tympanic 
wings ; ” when ossified, they become pneumatic. 
The alisphenoids (al.s.) are very remarkable : their broadest part is proximal, but 
they dilate again at their outer, free edge, after becoming narrowed in by one-fourth at 
their middle. Their front margin, which helps to form the sphenoidal fissure, is 
concave, and their postero-external edge is cut away, so to speak, by the large 
pupiform cochlese (chi.), around which the posterior edge of the aiisphenoid is carefully 
bound. The hind margin is a large right-angled notch ; the outer edge is sinuous, 
rounded, and looks forwards and inwards ; all this outer part is swollen, but perforated. 
