398 
MR, W. K. PARKER OR THE SKELETON 
Close behind the hard cartilage of the basi-hyal, the hypo-hyal end ( h.hy .) of the 
descending hyoid bar is there continuous both with the hard and the soft cartilage; 
and behind it, in its axil, the lesser bar, or 1st cerato-branchial ( c.br\ ) is attached,— 
semi-confluent. The 2nd basi-branchial (Plate 16, fig. 3, b.br 2 .), is a thickish rod of 
hard cartilage serving for the attachment of the oblique muscular mass of the lingual 
apparatus ; it is broad in front and narrow behind, and moderately thick. Muller, 
who let nothing escape him, figures a triradiate tract of soft cartilage on the “ oesophago- 
cutaneous duct” (I., plate 7, fig. 5). I find a similar piece (Plate 16, fig. 7, d.ce.c.). 
This is extremely interesting and instructive, for it is all we have in this type—(I do 
not find it in Myxine ) —of the huge “extra-branchial” basket-w T ork of the Lamprey, 
which can already be seen in embryos one-fifth of an inch in length. Thus, if the 
Myxinoid is a sort of Ammoccete, it is an Ammoccete with a difference. 
On the supra-lingual apparatus of Bdellostoma. 
In these structures, again, we have a curious generic difference between Bdellostoma 
and Myxine; this series of intra-visceral arches is, however, only gently modified in 
the former from that of the latter (see Plate 12, fig. 8; and Plate 16, fig. 5). 
Here, there is no differentiation of the median bar; the middle, in front, projects 
forwards as a triangular tongue of cartilage, but not behind the last lateral bars; the 
middle, there, is merely a soft narrow tract. The first pair of partly-segmented 
arches is the largest in this type, only the margin, all round, is soft; it ends in 
two soft incurved horns. The second pair of bars is soon lost in the third, which are 
almost as large as the first, and are quite hard, except the middle, or connective tract. 
I see no horny points in the front part of the common ligamentous tract in front, 
such as we saw in Myxine (Plate 12, fig. 8). A deep fissure divides the first pair 
of arches from the other two ; they are only separated across the middle for one- 
tliird of their extent. The richly golden, lanceolate teeth (Plate 16, figs. 4 and 6), 
show two rows, right and left, of more equal teeth than in Myxine (Plate 12, fig. 7); 
there are eleven in each of the four rows ; I counted seven on the outer, and nine 
on the inner rows in Myxine. The single upper tooth attached to the ethmoidal 
region of the skull is a very large “ canine,” hooked backwards (Plate 16, fig. 6 ; and 
Plate 17, fig. 3, et.t.). 
On the sense-capsules and barbels of Bdellostoma. 
The auditory capsules (Plate 16, figs. 1,6; and Plate 17, figs. 1-3, au .) in this 
type also are very small, and composed of hard cartilage; they are quite confluent 
with the contiguous parts of the skull; seen from below (Plate 17, fig. 3, au.), they 
are of a full oval form, and their long axis is almost parallel with that of the skull, 
but looking a little inwards in front. Above (figs. 1 and 2, au.) they are reniform, 
on account of the deficiency of cartilage in the great “meatus interims;” these 
