140 
MR. W. K. PARKER ON THE STRUCTURE AND 
In the architecture of their skull they are as nearly much contrasted as any two 
species that can be found in the whole group of the Anura; we shall see how much of 
this is due to the feeble condition of one, and to the stout, stony strength of the other. 
In the skull of Pelobates (Plate 25, figs. 5-11) the length of the skull as compared 
to its greatest breadth is only as 7 to 8§; the occipital condyles project so far beyond 
those of the quadrate that the median length is one fourteenth greater than the 
extent of the skull at the sides. 
Here we miss the excessively wide gape of Xenophrys and the American Bull¬ 
frogs ; there, all was for elasticity ; here, all is for compactness. 
The occipital region is moderately wide'; the great width of the skull is mainly due 
to the suspensorial structures (sq., q.). 
The endocranium, best seen from below, and the end (figs. 6 and 8) is wide, but 
not fiat as in Xenophrys (Plate 23, figs. 5-7); yet it increases in width from behind, 
forwards, as in that type; it has also a very broad but short nasal region, which is, 
as in Xenophrys, a well-fused convex mass, with a thick, short, decurved “prenasal 
rostrum” overhanging the front; but the premaxillaries under the skull are more 
normal. Strong as are the outworks (ectocranial elements) of the skull, the equally 
strong endocranial territories can be made out very clearly, on the whole, without 
unroofing. 
The occipital condyles (figs. 6 and 8, oc.c .) are large, sub-reniform, postero-inferior 
in position, and separated by a space two-tliirds their width, which is gently emar- 
ginate. The whole oceipito-auditory region, right and left, is completely ossified up 
to the foramen ovale (V.); the super- and basioccipital tracts of cartilage are quite 
obliterated. There is cartilage from the front of the foramen ovale to the front of the 
optic fenestra (II.), and then the girdle-bone ( eth.) occupies all but small supero-lateral 
tracts in the front; the sides of the nasal region, only, are unossified. The girdle-bone 
thus occupies the fore part of the orbito-sphenoidal region, all its own territory, and 
all the middle part of the nasal. 
Yet the terminal part was probably formed by a separate centre (or centres), 
as in Xenophrys, anchylosis taking place afterwards. 
From whatever aspect the endocranium is examined (figs. 5—8) great strength is 
seen, the end view (fig. 8) especially shows how strong the occipital arch is, terminated 
by the large condyles, and flanked by the massive auditory capsules. These show the 
large arches of the canals (a,s.c., h.s.c., p.s.c .) ; on the outside right and left, the two 
“tegmina” (fig. 5) are clamped by the large squamosals (sq.) as in a vice. 
The outspread girdle-bone (eth.) has shallow “axils,” and sharp angular wings; 
these articulate with the palatines (pa.). The ali-nasal cartilages (figs. 5, 7, al.n, 
n.w.) are crescents of cartilage outside the double bony roof, nasal and prenasal; and 
the external nostrils (e.n.) are half embraced by their concave edge; these openings 
are well finished in front and at the side by the normal inner and outer upper labials 
(v.l l :u.P.). Below (fig. 6), we see that the bifurcate cornua trabecula)—pro-rhinals 
