126 
MR. W. K. PARKER ON THE STRUCTURE AND 
Between these front paired vomers, the proper azygous vomer (v .), which only appears 
in highly specialised types—as Teleostei, Chelonians, certain Birds, and Mammals— 
passes its fore end between and above the paired bones, and then becomes carinate 
to rest upon the hard palate; it widens behind to support the olfactory capsule, where 
are developed the so-called “ middle turbinals.” 
The aliethmoidal, or the olfactory region ( al.e .), is divided right and left into a 
large antero-superior lobe and a small postero-inferior. The latter contains the 
hinder part of the middle turbinal folds ( m.tb .), and the former the whole of the 
upper, and the fore part of the middle turbinals. A deep, sinuous valley is seen 
between this bilobate swelling, right and left, and the great orbitosphenoidal wings 
(' o.s.), whilst, laterally, the cranium is narrowed behind the lateral ethmoidal region, 
and then swells out still more in the orbitosphenoidal. All the sinuosities of the 
lateral outline of the endocranium are gentle and very elegant; there are several in 
the auditory and occipital region, where the “ stern ” of the barge-like skull narrows in. 
The nasal labyrinth, on its lower aspect, shows some of its complexity through its 
fissures ; where the floor of the capsule is bound by the vomerine forks ( n.f. , v.), there 
it is seen to run forwards, right and left of the vomer, as a spike of cartilage. 
This will be seen in its full size in the sections ; I have called it the “precurrent 
cartilage” (see fig. 8 ,pc.c.); it may reach the recurrent cartilage (rc.c.), as in Orycteropus; 
here, however, it does not quite reach it. In the hooked angular space between the 
larger and lesser swellings of the ethmoid the foremost outgrowth of the middle 
turbinals (m.tb.) can be seen. 
Between the forks of the vomer the basicranial beam shows itself; here it is com¬ 
posed of all the three prepituitary rods, trabeculae, and intertrabecula ; its anatomical 
names here are perpendicular ethmoid ( p.e .), between the forks of the vomer ; pre¬ 
sphenoid (p.s.), for a short distance behind the forks; and basisphenoid ( b.s .) still 
further back, where it is perforate ; a primary, oval, pituitary opening being left at this 
part. Right and left of that space we see the “ sphenoidal fissure,” which allows a 
number of cranial nerves to escape—third, fourth, part of the fifth, and the sixth. 
The great orbitosphenoid (o.s.) has its moderately broad base or proximal part 
divided off from the presphenoid merely by an inferior groove ; it curls round behind 
the ethmoidal masses (al.e.), widening, expanding, and becoming convex. Nearly 
half-way towards the outer margin is seen the optic foramen (II.), which lies nearer 
the hind than the front edge of the band. The free upper edge of the orbitosphenoid 
(o.s.) is not seen in this figure (see fig. 2), but it can be seen that the wide upper part 
is continuous with the nasal capsule (al.e.) in front, and with the supra-auditory 
region of the side wall of the skull (s.a.c.), behind. 
In this early vegetative state of the endocranium there is something very fiower-like 
in its various parts, both as to their shapes and their development. Right and left of 
which is only partly supported by the feeble, and sometimes detached, recurrent cartilage. Tbe fact is 
that these curious and enigmatical organs dominate different skeletal parts in different types. 
