DEVELOPMENT OF THE SKULL IN THE URODELES. 207 
(fig. 2,7. n). The ethmo-palatine cartilages (e.pa) have coalesced with their hinder 
margin below; and the palatine bones (pa) show no tendency to apply themselves to 
them, their proper endoskeletal correlates. The internasal cartilage (i.n. ¢) is now a 
narrow truncate band with its convex margin behind, and is much reduced from its 
former relative size. This retrograde metamorphosis is consonant with that of the para- 
chordals and parachordal region of the trabecule: at first there is no intertrabecular 
structure, and only the apices of the trabecule run to the mid line; afterwards all the 
hind skull is floored, and a wide internasal band appears in front of the orbits; then, 
in the adult, the two halves of the endocranium are only held together by a narrow 
parachordal band: behind, and a narrow intratrabecular band in front. 
The direction of the suspensorium is what it was at the first, viz. forwards, as well as 
outwards and downwards; this is extremely unlike what we see in the Frog, where its 
direction is at first quite forwards, and then changes so as to be directed backwards 
very considerably. 
Indeed the metamorphic range, even in the Caducibranchiate Urodeles, is very small 
as compared with that of the ordinary Anura: they do not spring from so low a root, 
by far, and they do not rise so high, by far, as the Frogs and their kindred. 
The suspensorium, by its ascending process (fig. 6, a. p), retains its fusion with the 
alisphenoidal wall; but the pedicle proper (pd) is a bulbous condyle which rolls in 
the concavity of the basipterygoid plate (4.pq). 
The otic process (ot. p) is a thick pedate mass of cartilage, continuous below with the 
main body of the cartilage, not affected by the quadrate bone (¢g), which runs forwards 
into the pterygoid cartilage (¢.pqg) a narrow filiform process. 
c. The Free Arches of the adult Newt. 
The hinge (q. ¢) is a reniform and convexo-concave condyle, corresponding with the 
sinuous condylar surface of the mandible (figs. 3, 3°, a. c); Meckel’s cartilage is 
persistent; but the proximal part is considerably ossified by the embracing articular 
bone, in the trough of which it lies. 
Only the ceratohyal (fig. 7, c.hy) is developed in the next arch; it is a spatulate bar, 
rounded above and ossified (more than halfway down); the rest isa flat pyriform region 
of cartilage, the narrow end of which is attached by a hypohyal ligament to the 
unossified end of the first basibranchial (6.07'), which alone represents the basihyal 
segment. This basibranchial (4.7) is not segmented, but the hinder part of it is left 
unossified ; the whole bar is a strong compressed rod. 
The remnants of both the first and second branchial arches (e.6r’, ¢.br’, ¢.br’) are 
attached to the soft part, the former to its middle and the latter to its end. The first 
bar has two, almost equal, ossified segments, and is large; the second arch is a feeble 
bar, bowed inwards and backwards, and is only composed of the ceratobranchial 
element (c.dr?); it is fastened above to a spur on the lower end of the epibranchial of 
the first arch. 
