554 
ME. W. K. PAEKEE ON THE STEHCTHEE AND DEVELOPMENT 
cJiondropterygoid, and then, having become the apex of that process, degenerates 
into fibrous tissue*. 
In the fifth stage (Plate 22. figs. 6, 7) the suspensorium gave forth nothing from its 
front margin, but now there is a long tongue of cartilage (Plate 24. figs. 1, 2, pg.), the 
chondropterygoid. This process in its development in the Urodela is curiously like the 
modifications and stages of the symplectic process of the hyomandibular in Fishes (see 
Gegenbaue, s Selachians,’ p. 175, figs. A, B, C, D, E). I have missed that stage in Siredon 
in which the pterygoid was budding, answering to fig. B in M. Gegenbaue’s woodcut, 
but I have seen and drawn this stage in larvae of Spelerpes and Triton . 
The larvae of Batrachians throw no light upon the interpretation of the pterygo- 
palatine arcade ; for in them it is at first, and indeed for many days, merely a conju- 
gating band between the ethmoidal region of the trabecula and the distal part of the 
suspensorium f. 
So that, equally belonging to both bars, in the larval state, it has to become deve- 
loped into its adult condition before it teaches any thing. In the Toad (see my last 
paper) it becomes very instructive, and shows, at least, the independence of the ethmo- 
palatine. 
The huge mandibular pier, which has sucked the life out of the pier of the hyoid 
arch, now holds to the skull by the broad band of cartilage that has become completely 
welded to the skull-wall. But below this “ ascending process ” the “ pedicle ” ( pd .) has 
grown into a ball-shaped bud, which is made to sink into a socket of cartilage just where 
the trabecula is fused with the ear-capsule ; it rests on a bed of fibrous tissue, for there 
is here (contrary. to what we see in the Frog) no joint-cavity (figs. 2, 4). 
The otic process ( ot.p .) is a blunted triangular mass of cartilage, strapped by a fibrous 
ligament to the ear-sac, and held down by the lathy, splintery squamosal (or preopercular). 
The ear-capsule at this stage corroborates the older views of the writer, namely, that 
the stapes is cut out (or segmented off) from the preformed cartilage of the ear-capsule 
in the Urodeles. In the last two stages (Plate 22. figs. 4, 5, 6, 7) the inner and ante- 
rior part of the fenestral cleft was fringed by ragged cartilage ; it is now (Plate 24. 
figs. 2 & 4, st.f.o .) ragged no longer. 
There is now a half-severed flap of cartilage, like a stonecrop-le&f, which serves as a 
stapedial lid to the vestibular fenestra. 
The study of the development of these parts in various Urodeles shows how it is that 
the pedicle in its stunted condition ( primary in the Urodeles, but secondary in the 
Anura) articulates with the prootic region of the ear-capsule. 
The young of Triton cristatus shows clearly that as soon as the parachordal cartilage 
* At present I am not aware of any thing hut a membrane-hone in this part of the palate in Snakes, Lizards, 
and Crocodiles — the “ os transversum,” or osseous transpalatine. The early embryos of Serpents have failed 
me here; but the development of the skull in the other Beptiles has only very partially been worked out by me. 
f Professor Huxley will bear me witness that I am not the only morphologist whose mind has oscillated 
(not once or twice) as to the independence, or the secondary nature, of the pterygo-palatine arcade. 
