5 
418 MR. W. K. PARKER ON THE SKELETON 
(see my 3rd Paper, Plate 30, fig. 2 ; and Plate 34, fig. 8), the epidiyal end of the long 
hyoid “ tape ” when it has got under the emerging 7th nerve, does not, as usual, unite 
with the skull, but with the back of the pedicle, behind the part where the pterygoid 
is given off in front. 
Here, as a secondcny development, we get exactly what we have fiom the first id 
the Lamprey ; and I could give numerous instances of cases of this kind; homologous 
parts being continuous with some neighbouring cartilage in one type, and becoming 
confluent in another. 
The rather thick styliform (epi-cerato hyal) bar of the Lamprey curves gently 
upwards, as it passes downwards and backwards; it ends below in the cornual 
part or cerato-hyal (Plate 18, figs. 1 2, 5, 6, 7, c.hy.). This part is not segmented 
from the epidiyal region ; but it is quite distinct from the basal bar ( b.hy .). 
The latter bar is strongly clamped by these two horizontal growths, each of which 
is roughly liatchet-shaped, the blade being turned outwards from the hind part, and 
the handle growing forwards as a strong styloid process. The thickish blades are 
convex below, concave above, and a notch is seen between them and their handles; 
the epi-hyal grows into the top of the outer angle of the blade, which latter 
part is obliquely perforated in front of its middle. 
The facial nerve (Plate 18, figs. 1, 5, VII.) emerges behind the pedicle ( pd .), 
and then passes to the inside of the forking cartilage. 
The median hyoid bar passes from the circular opening of the mouth to a point 
half-way between the 1st and 2nd branchial clefts (fig. 1, b.liy.); when dissected 
out it presents the appearance shown in figs. 6-8,—lower, upper, and side views. 
This rod is not straight, but bent sinuously from side to side, and is upturned both 
before and behind ; it is oval in section, and has an irregular, half soft, keel in 
the hinder part, where it is clamped by the cerato-hyals. Narrowing into a neck 
towards the front part, it enlarges at the end into a head, the hind part of which 
is soft cartilage, and the fore part hard. That hard part is in three pieces, 
separated by soft synchondrosial tracts. The side pieces form a short trough, and 
are uncinate blades, united by the convexo-concave lower piece. These parts, which 
look like the mandibles of a Beetle, have a pair of supra-lingual cartilages over them 
(Plate 14, fig. 10) ; and also between the cerato-hyals there is a curious framework 
to the “ lower velum” (Plate 18, fig. 7 i.v.s.) ; these parts I shall describe soon. 
3. On the extra-branchial basket-work. 
In the Myxinoids the only trace of extra-visceral cartilage found was in the 
“ ductus oesophago-cutaneus ” of Bdellostoma (Plate 16, fig. 7) ; Petromyzon , on the 
contrary, is remarkable in having the largest and most perfect framework of this 
kind known. 
In Tadpoles, behind tire three branchial openings, and in front of the first, there 
