388 
MR. W. K. PARKER OK THE SKELETOX 
wards, and are sub-pyriform in section, the thick end being uppermost. This 8th 
section is the first that takes in the lower lip, and we see how truly Ammoccetine these 
Myxinoids are. 
Section 9 (fig. 9).—If this section be compared with the dissections we shall see 
what an elegant structure the nasal capsule ( ol.) of Myxine is; in my Second Part I shall 
show that in the Lamprey this organ is a complete wheel of plates in section; here it is 
only half a wheel, and the folds only gently converge; this is the most simple structure 
of the two. Yet on this simpler platform there is a most curious specialisation of the 
cartilaginous capsule itself, and also of its vestibule. The accuracy of the grating is 
well shown in the sections. The two lowermost of the nine parallel bars are the widest; 
each bar has its own fold of mucous membrane, and these nearly reach to the common 
cavity below, which is here very large. Supporting this curious framework, we see the 
palato-trabecular bands ( p.tr ., see also Plates 9 and 10); these are hard, oval, and tilted 
outwards, above. Then, for a short distance in front of the cranial cavity, the floor 
of the cranio-facial framework is open, being only floored by membrane. 
A large tract of palatal tissue intervenes between this weak floor and the roof of the 
mouth (in.), the cavity of which is formed of three fissures, the outer and upper pair 
being semicircular, and the median, or lower, sub-oblong, but widest above, and 
having its sides running between deep folds. Above, the median line of the mouth is 
grooved ; below, it is gently ridged ; the lateral folds are the fore part of the supra- 
lingual framework. The proper lingual cartilages ( h.hy a .) are now seen to be four, 
instead of two, for the median pair have come into view (see also Plate 9, fig. 3) ; the 
apparent distance between the bars, here, is due to the fact that only the projecting 
lore end of each was cut through. 
Section 10 (fig. 10).— This section is very similar to the last, but is important as 
showing the fusion of the two median bars ( b.hy. a ); in this old specimen the fusion is 
perfect, but in the one dissected there was some appearance of distinctness along the 
midline, below (Plate 9, fig. 3) ; here the edges are thicker than the middle, which 
is gently scooped. 
Section 11 (fig. 11).—Several new things come into this section; and here in the 
middle of the nasal capsule the lower cartilaginous bars are seen to have their own 
fold, but it is not free, so that there are only seven distinct folds in the sac. The 
great inferior fontanelle of the cranium bulges gently here, and the tip of the hinder 
intertrabecula ( p.i.tr .) is cut across, where it supports the middle of the mem¬ 
branous floor. The bulging of the floor makes a great space for the nasal cavity ( n.c .). 
The palato-trabecular bands [p.tr.) are smaller at this part, and evenly oval in 
section; between the skull and the roof of the mouth there is a considerable web ol 
fibrous tissue. 
The form of the mouth cavity here is greatly modified by the horny cheek-teeth— 
supra-linguals (s.l.t .)—which are imbedded in a mass of fibrous stroma, and thus the 
wide mouth becomes a space of three fissures. 
