DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 
19 
proper vomer (v.) is now a large trough of bone composed of several laminae. The 
nasals and the max diaries (mx.) are still seen in section, and below we have the 
dentary with its increasing laminae, and Meckel’s cartilage (ink.). 
10 th Section (Plate 3, for fig. 9a. read 10)-— This is from a very slight distance 
behind the last, it is given to show how soon the nasal turbinal ( n.tb .) becomes free 
below. In both this and fig. 9 the glandular crypts ( gl.c .) are seen to be increasing in 
number, and to be crowding between the Schneiderian membrane and the cartilage. 
11 th Section (Plate 3, fig, 11).—Here we see that the most complex part of the nasal 
labyrinth lies beneath the cribriform plate ; the olfactory fibres (I.) are here seen 
entering from the olfactory lobes or “ rhinencephala ” (C w ). The septum here is the 
perpendicular ethmoid (p.e.) ; it is thinuish above, and very bulbous below ; the crest 
above is the “ crista galli.” 
The floor of the fore part of the cranium is here only perfect near the septum ; but 
the cartilage increases, laterally, so that the olfactory nerves then pass through holes, 
and not through chinks as at present (see Plate 2, fig. 5). Here the upper part of 
the labyrinth answers to the upper turbinal in Man, and the lower part to his middle 
turbinal. The cartilage at this part encloses a large oblique oval cavity, round which 
a perfect ring of glandular crypts are packed. The inner process of cartilage, which 
runs free from that ring, is the hinder or proximal part of the free precurrent cartilage 
seen in the last two figures (see fig. 9a, pc.c.). 
Here we see that, behind, the recurrent cartilage ( rc.c .) protecting Jacobson’s organ 
overlaps this curious fore-growth of the middle turbinal, for its section is still seen 
above the edge of the vomer (v.). 
The bones seen above the labyrinth are no longer the nasals, but the frontals (see 
Plate 2, fig. 7, f), which are very large plates in this type, whilst the nasals are 
rather short. The maxillaries (mx.) are very large, and have many laminae at this 
part, and the palatine plates (above m.) nearly meet at the mid-line. But between 
the frontals and maxillaries there is the huge lacrymal (l.; see also Plate 2, fig. 8), 
which has a facial as well as an orbital plate. 
Meckel’s cartilages (mk.) are seen below, with their protecting dentaries ( d.) which 
- are developing a considerable amount of diploe, here, at the middle of the ramus (see 
Plate 2, figs. 3 and 8, d.). 
12 th Section (Plate 3, fig. 12).—This is through the fore part of the hemispheres 
(C 1 ' 7 .) and of the eye-balls (e). The nasal roof is cut through behind the cribriform 
plate (see Plate 5, fig. 1), and this part of the nasal labyrinth is sub-cranial, and the 
proper cranial walls are above, and external, to this part of the turbinals which are 
reduced to two folds. The outer of these folds of the middle turbinal (m.tb.) is fixed, 
both above and below, the inner is free, above ; they are both turned inwards and 
upwards. This part of the capsule has, in some degree, coalesced with the septum 
(p.e.) both above and below; its very bulbous form at the base is well shown ; this is 
the last figured section that shows only the intertrabecula. Indeed, even here, it is 
