394 
MR. W. K. PARKER ON THE SKELETON 
the cartilage seen in it is mainly that of sections of the terminal rays of the basket- 
work ( e.br h, p.br 1 ’ 2 .), with the very last part of the hyoid bar ( h.hy .), and, above, 
the upper part of the 1st branchial (< e.br h) is cut through twice. The 1st basi-branchial 
almost closes upon the median bands (belonging to the huge lingual muscles) that 
lie inside it. This section was made between the 1st and 2nd spinal nerves (Plate 9, 
figs. 1, 2) ( sp.n .), and here the notochord (nc.) is of full size, and has no cartilage 
around it, whatever ; the parachordals are the only paraxial cartilages developed ; and, 
as in the larval Lamprey, there are no rudiments, even, of vertebrae; here, for C 3 ., 
read my. 
Beneath the huge lingual muscles, the intra-branchial skeleton breaks out again; there 
(Plate 9, fig. 4) the 2nd basi-branchial (6.hr 2 .) reappears as a band of hard cartilage, 
broadish in front, and narrower behind, it is ventrally placed in relation to the first 
two branchial pouches ; it does not support them, but lies under the “ raphe ” of the 
hinder part of the massive muscular apparatus of the tongue (l.m.m.). 
The foregoing are all the skeletal parts I can find in this Fish, which in some respects 
is developed more in conformity with the higher Fishes—Cartilaginous or Bony—than 
the Lamprey, and in others is so very rudimentary ; altogether, it evidently belongs to 
the Ammoccetine type, although greatly specialised in its own way, to its own ends. 
The sections just described will be equally useful for both Myxine and Bdellostoma, 
for this latter larger Fish differs only in non-essentials from Myxine; my description of 
the former will merely relate to dissections, and to a general longitudinally-vertical 
section of the Fish. 
On the skeleton of Bdellostoma Forsteri.* 
On the craniofacial apparatus of the adult Bdellostoma Forsteri. 
The theca cranialis, or dura mater, in the hinder half, and the nasal capsule in the 
front half of the cranium (Plates 16, 17), have to be removed before the proper 
framework can be seen from above ; the lingual apparatus has to be dissected from 
the lower part of the head before the basal part can be seen. Neither in the adult of 
these two types, nor in the embryo of the somewhat higher Lamprey, do we see any 
other explanation of the pre-pituitary part of the cranium than that of an outgrowth 
or foregrowth of the axial part of the skull. And yet the pro-chordal part begins 
* Dr. Gunther informs me that there is but one species of this Fish, and that the kinds called B. 
Forsteri and B. heterotrema, by Muller, are merely varieties of the same species. Dr. Gunther’s descrip¬ 
tion of the two Myxinoid Genera is as follows :— 
“Myxine. —One external branchial aperture opening only on each side of the abdomen, leading by six 
ducts to six branchial sacs. 
“Bdellostoma. —Six or more external branchial apertures on each side, each leading by a separate 
duct to a branchial sac.” (‘ Study of Fishes,’ p. 695.) 
Muller, I., plate 7, fig. 3, gives a figure of Bdellostoma with seven pouches on the left side, besides the 
“ ductus cesophago-cutaneous,” and only six pouches on the right side. I found only six pouches on each 
side in my two specimens; iov plans of these remarkable branchial organs see the same plate in Muller’s 
Memoir. 
