390 
MR. W. K. PARKER OK THE SKELETON 
* 
section. The cheek-teeth are cut through nearer their point, and their enclosing 
cartilage is cut across through the first pair of fissures (fig. 8), so that it is not in one 
piece, as in the last section, but in three. The basi-hyal ( b.hy a .) shows some soft 
cartilage where the two pairs of front bars unite again, behind the median fenestra 
(Plate 9, fig. 3), in front of the merely double part. 
Section 16 (Plate 12, fig. 5).—Here we have a section of the hinder intertrabecula 
( p.i.tr .) where it is confluent with the hind part of the trabeculse; this is for a very 
short extent (Plate 10, fig. 3), but the actual union is very instructive, for in these 
Myxinoids this median bar retains that distinctness from the paired bars, which, in other 
types, is a very temporary condition. (See in the young Lamprey, Plate 10, fig. 5, 
tr., p.i.tr.) At this point the basis-cranii is perfect, and being across the subocular 
fenestra (Plates 9, 10, s.o.f.) the cranium and pterygo-palatine region of the face are 
distinct for a short distance. 
The supra-lingual skeleton (see also fig. 8) shows the depth of the middle part, and 
the steepness of the two sides further back across the two first fissures. The basi-hyal 
is now single (Plate 9, fig. 3, b.hy p .), but this is down-bent in the middle, where two 
pieces have coalesced. 
Section 17 (Plate 5, fig. 6).—This is also through the suborbital fenestrse (between 
tr. and pa.) behind the junction of the hinder intertrabecula with the trabeculae 
[p.i.tr., tr.). The pterygo-palatine bar [pa.) is dipping more and more towards the 
quadrate region ; the lateral supra-lingual plates are narrower, and the basal part 
broader and deeper than in the last; the double basi-hyal [b.hy p .) is narrower and 
deepeia 
Section 18 (Plate 13, fig. l).—In this section, behind the middle of the subocular 
fenestra [s.o.f.), a bundle of fibres is seen emerging from the brain; this is the optic 
nerve II., with the aborted eye-ball at its extremity. Here the trabecula [tr.) is a 
narrow rod, and the pterygo-palatine (pa.) is becoming flat and descending. The 
naso-palatine canal [p.n.c.) is still very wide, but the intertrabecula [p.i.tr.) below it 
is narrowing. This and the two next sections are through the hard cartilage of the 
hinder bars of the supra-lingual framework; the lateral plates are narrower, and the 
basi-hyal [b.hif.) similar to what was seen in the last section. 
Section 19 (Plate 13, fig. 2).—This is the last section through the subocular fenestra 
[s.o.f.); it is very similar to the last, but the intertrabecula [p.i.tr.) is much narrower, 
and the pterygoid [pg.) is very solid; the basi-hyal [b.hif.) is becoming narrower, and 
the supra-lingual [s.l.c.) shows soft cartilage below, between the two hard bars (see 
Plate 12, fig 8). 
Section 20 (Plate 13, fig. 3).—This and the next are between the first and second 
fenestrse, and therefore through the “ pedicle ” [pd.) of the pterygo-quadrate region 
(Plates 9, 10, pg., q.) ; there is soft cartilage here, but with some hardened cells 
inside it; the trabeculae [tr.) are widening towards the parachordals, and the inter- 
trabecuke [p.i.tr.) under the narrowing naso-palatine canal [p.n.c.) are becoming small. 
