OF THE MARSIPOBRANCIT FISHES. 
383 
in the Lamprey with one row of teeth right and ieft (Plate 14, fig. 9) ; in both cases 
these are peculiar to the Marsipobranchs. 
When the great lingual cartilage, with the parts carried by it, is dissected out we 
have the structure shown in Plate 1 2, fig. 7 ; and when the teeth are removed, then 
the “ supra-lingual ” framework is seen (fig. 8), a curious apron with slits in it, and 
short strings projecting from it; it is composed of hard and soft cartilage, and of 
fibrous tissue ending, in front, in a horny comb ; the figure shows it as considerably 
outspread, for display ;—the sections correct this. In this hollow space lie the lingual 
teeth (fig. 7, s.l.t.) ; the cartilage had better be described first. This additional skeletal 
structure is formed in the floor and sides of the oral mucous membrane, and, with the 
structures it carries, reduces the cavity to a number of narrow chinks. The general 
outline of the supra-lingual frame-work is heart-shaped, but widely open, with pro¬ 
jecting spurs, behind, whilst in front it is transverse, slightly emarginate, and developed 
into a fine comb of horny spikes. The fore part is membranous, but the cartilage 
creeps into this membrane, right, left, and in the middle—most there; there the fore 
margin of the cartilage has a small, toothed emargination in the middle and a large 
transverse notch, right and left. The whole cartilage tends to break up into a series 
of three pairs of short arches ; within the hinder half there is a median bar between ; 
these, together, form a sort of intra-visceral series, mimetic of the proper visceral 
arches, just as the extra-visceral framework of the Lamprey’s pharynx is mimetic of 
such a series. 
The first pair of these semi-segmented arches is wing-like, and is half separated by 
the next pair, which are narrow and feeble; one snag ends both of these behind ; a 
crescentic cleft divides these for three-fourths of their extent ; these two first pairs 
are composed of soft cartilage. The hinder pair ends in a snag, which is soft, and 
which is continuous in front with the root of the first snag. The side bars are twice 
as large as those in front of them, and are composed of hard cartilage; the median 
bar is soft, projects a little into the notch in front of it, and much more behind, where 
it reaches nearly as far backwards as the second pair of lateral processes. As it lies 
on the large basal beam, this hinder median part reaches as far back as the hard 
cartilage, and further than the setting on of the hypo-hyal ends of the hyoid arches 
(h.hy.). 
In front, the horny comb helps to fill in the emargination of the basal beam." The 
arrangement of the golden-coloured horny supra-lingual teeth is in a double, arched 
| series, with a large notch behind. There are seven large teeth and nine small ones on 
each side; the large teeth are in front of, and outside, the others ; their points look 
* There may seem to be some discrepancy between the figures of the huge basal beam—upper, lower, 
and lateral, and of the sections that illustrate its structure still further. The explanation is this: the 
dissections show the bars as invested with a strong perichondrium, and thus they look nearer together than 
j they really are. The colouring of the dissections takes no account of this : the numerous sections, drawn 
with a camera, show the width of the intercartilaginous spaces. 
3 d 2 
