i 
438 MR. W. K. PARKER OK THE SKELETON 
seen, and below it, that part of the extra-hyal ( ex.hy .) which fastens on to the top of 
the epi-hyal bar is cnt across, and, lower down, the main bar of this superficial soft 
band. The angle of each cerato-hyal ( c.hy .) is cut across and the basi-hyal in its 
basi-brcinchial region (b.br .). Three cavities are severed, lined with mucous membrane, 
one above another, in the mid-line—these are the posterior nasal canal ( p.n.c .), 
the pharynx, proper ( phx .), and the opening of the branchial canal ( br.c.). 
27 th Section (Plate 22, fig. 6).—This is through the. hind face of the auditory 
capsule (cm.) and the main mass of the vagus nerve (X.) Here the notochord ( nc.) is 
floored, but not roofed, and the limited investing cartilage (iv.) does not reach the 
auditory capsnle, but leaves a space for the vagus to pass through; thus the roof of the 
skull is gone, and most of the side walls. The extra-hyal is cut across as it goes 
back to join the general basket-work ; the basi-hyo-branchial region is cut through 
(b.hy .), and the angles of the cerato-hyals (c.hy.). The posterior nasal canal (p.n.c.) is 
lessening; below it we see the food-pharynx (phx.), below it the branchial canal (br.c.), 
and right and left of these passages the branchial folds of the first pouch (br.p.) 
28 th Section (Plate 22, fig. 7) is from the fore part of the spine, and through one of 
the foremost pairs of neural arches ( n.a.), which are seen to be large wedges of hard 
cartilage, with their upper end thick, and their lower end sharp, the section not 
reaching to their base. The notochord (nc.) has now its average size ; its sheath is a 
thick laminar membrane, like the cornea of the Mammalian eye-ball. The other part 
of the endoskeleton is the basi-branchial bar (b.br.) imbedded in the lingual muscles; 
above these masses are the branchial canal (br.c.), the proper pharynx (plix.), and the 
posterior nasal canal (p.n.c.) Outside the gill pouch (br.p., 1st or 2nd) the extra- 
branchial basket-work (ex.br.) is cut across in nine places; above, near the notochord, 
the longitudinal band uniting the arches above ; then, on the upper convexity, one of 
the spurs; at a distance below this the upper, and then the lower, cross band 
defending the aperture ; and then, below, one continuous tract of cartilage belonging 
to the lower part of a right and left arch, at their junction. 
29 th Section (Plate 22, fig. 8.)—This is very similar to the last section, and was 
taken not much further back. Here in a complete section of the neural cartilages 
(n.a.), we see that they are thickened at both ends. The posterior nasal canal (p.n.c.), 
is much folded ; this is its last appearance in the sections figured ; the other passages 
are as in the last section. The upper band of the basket-work (ex.br.) is cut across, 
also one of the snags, and one of the cross bars ; the other must have been cut through, 
but was hidden beneath the other tissues. Below, the common junction of the bars 
is cut across, between the bars, and bet’ween the median fenestrse. 
30 th Section (Plate 22, fig. 9).—Here we see the neural cartilages (n.a.) resting upon 
the sheath of the notochord (nc.) ; below this the great artery (ao.) is cut across, but 
there is no posterior nasal canal between it and the pharynx (phx.), which is well 
marked off from the branchial canal (br.c.) The lingual apparatus and the basi- 
branchial (b.br.), is still present; this is at about the first third of the great branchial 
