432 
MR. W. K. PARKER OK THE SKELETOK 
late above, and sharp below, the sharp part being invested with yellow horn—part of the 
dental series. 
4 th Section (Plate 20, fig. 4).—Both the cornu trabeculae (c.tr.) and the median 
upper labial (u.l 1 ) are broader than in the last, and the first lateral cartilage ( u.l 2 .) is 
cut through obliquely lower down. The annular cartilage (l.l 1 .) is cut across in front 
of its hind margin, and shows the concavity along its upper half. The hinder teeth ( l.t) 
are shown in the hollow of the divided labial disk. At the upper edge of the annular 
cartilage, right and left, there is a reniform tract of cartilage; this is the head of the 
lateral distal mandibular ( l.d.m .). The skeleton of the tongue (tg., b.hy'.) is now cut 
across, it is a thick slab of cartilage, with both surfaces slightly concave, and the lower 
face of less extent than the upper. 
5th Section (Plate 20, fig. 5).—This is from behind the annular cartilage, and through 
the hinder third of the great disk ( s.d .). The two great roof cartilages (c.tr., u.l 1 .) 
are very similar to the last, and the first lateral upper labial (u.l 2 .) is cut through near 
its lower end, and the foremost point of the second (u.l 3 .) is cut across. The lateral 
distal mandibulars (l.d.m) are now flat, with their upper edge turned outwards; 
between them, and near to them, arching over the hind part of the disk, two plates of 
cartilage are cut through, thick in the middle and thin outside ; these are the two 
sides of the fore part of the “ median distal mandibular ” (m.d.m), which is notched 
in its broad fore edge (see Plate 10, fig. 6) in the young P. marinus. Several 
cartilages are seen in the fore end of the tongue (tg.) ; of these the four larger tracts 
belong to the basi-hyal (b.hy., see also Plate 18, figs. 6-8) ; the short anterior median 
(b.hy'.), with the pair of short ascending pieces (b.hy"), and behind and under the 
middle piece the fore end of the main long bar (b.hy), which is elliptical in section in 
front, and placed with its long axis upwards. This section shows, what the general 
view of these parts does not, namely, that when these curious quasi-manclibles are cut 
through obliquely, their common basal piece is arched a little upwards. In the curious 
lingual cushions there is a small “ supra-lingual ” cartilage, right and left (s.l.c) ; its 
point is cut across here. 
6th Section (Plate 20, fig. 6).—The use of these various sectional figures ■will be 
seen by comparing this with the last ; there seems to be but little difference between 
them, but we miss some things seen in that, and find some new ones in this. The 
great leafy cornu (c.tr) is wider and flatter, the median upper labial (u.l 1 ) is very 
similar; the first lateral upper labials are gone, the section was made behind them, 
and the second (u.l 3 ) are larger points of cartilage between the two roof-plates. The 
flattened distal lateral mandibulars (l.d.m.) are vertical here, and the median carti¬ 
lage (m.l.m) is a single plate, slightly bent downwards where the basi-hyal rests 
on it. The main basi-hyal (b.hy.) is now much flatter and somewhat higher; the 
front short middle piece is not seen, but the erect pieces (b.hy") are cut across in their 
hind lobe, so that there is a considerable space between them and the main bar. The 
little cartilages inside these (s.l.c.) are larger, are elliptical in section, and in the valley 
