16 MR. W. K. PARKER ON THE STRUCTURE AND 
There is no complete nasal floor, except close behind the external nostrils, in front, 
and in the blind end of each capsule, behind, where the presphenoid lies between each 
space: the cavities, there, right and left, being the embryonic form of the “sphenoidal 
sinuses.” 
To make these numerous and complex figures more intelligible, the related parts 
are merely indicated; the skeletal structures are the parts to be brought into pro- 
minence.* 
1st Section (Plate 3, fig. 1).—This section is through the end of the snout at the 
opening of the nostrils and in front of the lower jaws. The broad upper part passes 
sinuously into a narrower lower part, which has a concave outline below. The 
septum nasi (s.7.) is complete, and has two narrow wings below, that belong to the 
floor (n.f.), and wide arched wings above (a/.n.), bifid at their lower edge. The section 
of the prenarial cavity (n.p.) is lunate, for there is here the beginning of the thick 
valvular cushion of the nostril. 
2nd Section (Plate 3, fig. 2).—This section is from behind the nostrils, but close 
to them; here the palatal hollow begins. 
The septum (s.n.) is thin in the middle at this part, and the alinasal roof-tracts 
are sharp at their lower edge. The two dilatations of cartilage below the septum are 
confluent here, and right and left of the solid foot there is a large pouch-shaped recess 
to the nostril (m.7.); this arial recess runs through several sections, showing that it, 
is of considerable width. At the top, the septum is beginning to dilate, and a 
valvular wing of the lining membrane is seen in this dilatation. 
The narial valve (n.v.) is very large here, and contains a section of a finger-shaped 
process of the alanasi. In the following sections this passes into the general cartilage, 
so that it is not a separate segment. 
The nasal bones (n.) come into view as far forwards as this section (see also Plate 2, 
fig. 1), for they run well over the snout. 
3rd Section (Plate 3, fig. 3).—This is through the whole fore face, for it takes in 
the top of the tongue (ty.) and the beginning of the lower jaws, where MECKEL’s 
cartilages (b.mn.) are confluent. The septum nasi (s.7.)is very thin in the middle, but 
is expanded above ; below, it stretches into a limited floor, flat below, and not far from 
the wide proximinal part of the valvular process, which supports the many-lobed valve 
(.v.). The nasal bones (7.) only are seen in this section. 
4th Section (Plate 3, fig. 4)—In this section the Meckelian rods (mk.) are 
separate, the dentaries (d.) are cut across, and a tooth-socket (¢.) is seen above each 
bone ; above, the nasals (n.) are seen. The septum nasi still thin below, is winged 
above, and these wings are the skeleton of a large upper narial lobe. The lower valve 
is smaller, but the whole passage is narrowed by folded thickenings of the lining 
* These sections, and the rest of the thin transparent stained preparations of this kind, were made for 
me by one of my Sons, and the camera drawings of them by another; about one-sixth of the 163 
sections made of this one head were drawn; only three-fifths of each drawing has been engraved. 
