382 
MR. W. K. PARKER OK THE SKELETON 
growth in the Lamprey ; in that Fish the reticulation is formed outside the head- 
cavities ; in the Hag-Fish they must have been formed within them, as they lie close to 
the hypo blastic lining of the throat. 
With regard to the great inferior median bar ( b.hy ., b.br.), there can be but little 
difficulty ; for not only the Lamprey, but the Bony Cfar-pike (Lepidosteus) also, shows 
us a similar huge glosso-hyal in front of the common basi-branchial bar. In the latter 
Fish (Phil. Trans., 1882, Plates 30-38) the basi-hyal is double, composed of two equal 
rounded rods, which are united along the middle. Moreover (most instructive of all 
the characters of that remarkable lingual skeleton), the cartilage is cut up into a number 
of transverse blocks by fibrous septa. This takes place in a Ganoid Fish, whose larva 
has a suctorial snout. 
In the Myxinoids the tongue dominates the whole body; everything else yields to 
it, and is modified intensely by it. In the Lamprey, as well as in Lepidosteus, the 
basi-hyal becomes double in front, here it is a four-fold bar or plate ; the solid cartilage 
being divided as it goes on expanding from behind forwards, first into two and then into 
four pieces (Plate 9, fig. 3) ; these are at once united and separated by tracts of soft 
cartilage or fibro-cartilage, and even by mere fibrous tissue in some places ; and the 
two inner pieces of the terminal front part have a fenestra between them, behind. 
Then the bar becomes sub-carinate, but this angular projection is gradually lost, and 
the cartilage suddenly becomes soft, and a mere thick, almost fibrous web, is continued 
backwards behind the hypo-hyal junctions as an anterior basi-branchial {b.br 1 .), which 
is one-third longer than the basi-hyal region. 
Near the middle, this soft fibro-cartilaginous bar becomes keeled and alate; it then 
lessens gradually to a sharp point, which is gently upturned ; this hinder part of the 
huge median bar is scooped on its upper surface ; but the scooping becomes deeper and 
deeper, as we pass forwards to where the great fourfold basi-hyal is carinate below. 
The two middle pieces, in front, together form an emargination, and the outer pieces are 
rounded off externally. In front, the great lingual bar is twice as wide as the alate 
part of the basi-branchial behind. This huge beam is swung from the head, in front 
of its middle, by those small, soft ropes, the descending hyoid bands ( c.hy .), which 
broaden and harden into the hyomandibular region ( h.m .), above. The broad, emargi- 
nate fore-end of the huge lingual cartilage nearly reaches to the tips of the lower 
barbels, two pairs of which are seen protecting the slit-like mouth ; whilst seven 
more protect the opening of the nasal proboscis (Plate 13, fig. 7). 
The supra-lingual apparatus of Myxine, 
The great basal bar (Plate 9, figs. 1-3, b.hy) is only the coarser part, so to speak, ot 
the lingual dentary apparatus ; the two rows of teeth, right and left, themselves are 
set in a cushion of fibrous tissue, which is supported by a supra-lingual cartilage 
(Plate 12, figs. 7, 8), a superadded structure, the rudiment of which only re-appears 
