5 
370 MR. W. K. PARKER ON THE SKELETON 
On the relation of the Myxinoids to other types: their Zoological position in the 
“ Branchiata,” or “ Anamniota.” 
Roughly, this may be expressed as follows : The Hag and Bdellostoma are a sort of 
greatly modified Ammocoete; they bear a relation to the Lamprey similar to that 
which it bears to the Anurous Amphibia. The secular losses among these types must 
have been very great indeed, for although the Marsipobranchs and the Anura—which 
are Marsipobranchs in their larval state—are akin to each other to a degree in which 
they are not akin to any other Branchiata, yet they are very far apart from each other, 
after all. The metamorphosis of the Tadpole lifts it far above the highest of the 
Marsipobranchii proper, but I feel satisfied that the Anura have only gradually become 
metamorphosed ; and I doubt whether all the larvce of Pseudis undergo that change, 
even now. Yet when once this change is set up, we see a very generalised and 
archaic Fish become almost a true Reptile. More than this, one kind— Pi pa —scarcely 
shows a trace of gills, and all the Anura, during their metamorphosis, develop a 
“bladder” which is, apparently, the rudiment of an “Allantois;” if further research 
makes this supposition a settled fact, the stride made by these forms, during individual 
life, will be seen to be very great indeed. 
It is better to call the Hag and Lamprey “ Marsipobranchs ” than suctorial fisixes; 
the adult Lamprey, like the Tadpole, is truly suctorial, but the mouth of the Ammocoete 
or larval Lamprey, and the mouth of the Hag and Bdellostoma, are not modified into 
a circular sucking ring, but it remains as a small hooded opening, fringed with short 
barbels, or oral palpi. There is no cartilage whatever in the mouth of the Ammocoete 
(Plate 19, figs. 4, 5), and in the Myxinoids the only cartilage developed is as a pith to 
the barbels (Plate 17, figs. 1-3). All this will be explained in the sequel, but we may 
as well start fairly, looking upon the subjects of the present paper as greatly specialised, 
but not metamorphised, “ Marsipobranchs,” a curious variety of arrested “ Sand 
Pride,” or Ammocoete. In my Second Part I shall show how such a simple type is 
transformed into a true Sucking Fish, or Lamprey, which may be, in turn, looked upon 
as a sort of highly specialised, but arrested, Anurous Amphibian. 
On the craniofacial apparatus of the adult Hag-Fish (Myxine glutinosa). 
All the cartilage to be found in this Fish is cephalic, for even the furthest rudiment 
of the dorsal part of the branchial basket is, like the rest of that system, supplied by 
a cranial nerve—the vagus ; the spinal region is only supported by membrane, or 
strong, fibrous tissue. 
Properly speaking, these Fishes, although Craniata, are not Vertehrata; they are 
chordato-craniata like the Lamprey before its metamorphosis, for neither in this, or 
in the large Cape species ( Bdellostoma ), can I find any cartilaginous rudiments of 
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