138 
MR. W. K. PARKER ON THE STRUCTURE AND 
therefore an uninjured oval, having no bevelling or emargination in front; it forms a 
fit lid for the vessel of the vestibule ( vb.). The stylo-hyal end of the hyoid bar 
(figs. 2 and 4, st.h.) is small, pedate, and articulates loosely with the ear-mass behind 
the almost closed first cleft. 
The mandibles (fig. 3) form an elegant arch ; the mento-Meckelian ( m.mh .) is not 
much developed; the dentary (cl.) is small, and the articulare ( ar .) is large, has a high 
coronoid crest, and within its trough behind the articular portion of Meckel’s cartilage 
has a large endosteal nucleus (fig. 3, ar'.), as in C/ielone viridis. The hyo-branchial 
structures show the same semi-transformed condition as the other parts of the skull, 
and some very generalised characters, besides. 
At first the stylo-ceratohyal band is narrow (fig. 3, c.hy.) ; it then widens largely, 
narrows again, has a knee-like dilatation at its fore part, and then goes straight back¬ 
wards as a narrow hypo-hyal ( h.hy.). 
The notch between the lateral parts of these structures is three times the extent of 
the solid basal plate ( b.li.br.) ; and this basal plate has a bony “basi-branchial” (lj.br.) in 
its centre. The thyro-hyals ( t.hy .) are normal, but the posterior lateral lobes are twice 
as large as those hinder forks, and instead of being a slight cartilaginous snag, they 
are large, and largely ossified. 
The anterior “ lateral lobes” are very large; they, also, have retained much of the 
larval cartilage, and each flabelliform outgrowth is notched deeply and sinuously in 
front. 
The investing bones are very similar to those of newly metamorphosed Frogs and 
Toads of the more typical sorts. The frontal portion of the two roof-bones (fig. 1 ,fp.) is 
merely a narrow lath, lying like a wall-plate on the flat top of the skull-wall; this ends 
at the second third of the interorbital region. The parietal portion widens, covers 
the hinder part of the large single fontanelle, spreads a little over the temporal region, 
runs sinuously over the hind skull, and ends some distance in front of the foramen 
magnum. The right bone overlaps the left, and the suture is very irregular. 
The nasals (n.) are large thin shells of bone, coming near each other by their round 
backs, and having two shallow emarginations outside. The premaxillaries (px.) are 
of great transverse extent, but their processes are feeble. There are no septo- 
maxillaries ; the maxillaries (mx.) are long thin bones, with a rather high shell-shaped 
fore end. 
The quadrato-jugals (q.j. ) are but little united to the quadrate; they and the 
squamosals (sq.) are feeble. The parasphenoid (fig. 2, pa.s.) is a short, wide, thin 
bone, normal in its processes, but ending far behind the antorbital region in a lathy 
ragged manner, like that of a young Common Frog. The vomers (fig. 2, v.) are very 
large, have a massive dentigerous lobe that nearly reaches the septum nasi, are coiled 
round three-fourths of the inner nostril (i.n.), and grow out in front to the suture 
between the premaxillary and maxillary. 
Here we have a combination of characters that betokens an old type and an arrested 
