DEVELOPMENT OP THE SKULL IN THE BATRACHIA. 
153 
distinct from tire continental form— II. malabarica. I have just described that species, 
and when this has been compared with it then all doubt will vanish as to their 
distinctness; both kinds attain the length of three inches, or thereabouts ; my speci¬ 
mens of H. malabarica are all young, and only a quarter the length of the adult; yet 
the ossification of their skull is much more perfect than in the adult of the Ceylonese 
kind; there are also other differences, as we shall see. 
This is a long skull (Plate 29, figs. 1, 2), for the length is equal to the breadth ; it is 
extremely like that of Polypedates chloronotus (Plate 26, figs. 1 , 2), but is not so long ; 
in that species the length is about a twelfth greater than the breadth; and that kind 
has its ossifications intenser, and has no evident superorbital “eave.” 
Although belonging to the narrow-skulled group of this Family, the cranium proper 
is in reality very broad, half as broad again as in an average species of Ranct, and 
therefore settling this as a character of the Oriental flat-toed Frogs. 
They are, indeed, a broad-muzzled, flat-skulled race, but when flattened most their 
skull is very Ranine as compared with that of a true Hyla. 
The occipital condyles (Plate 29, figs. 1, 2, oc.c .) are large, posterior, and separated 
by a crescentic emargination half their breadth. Measured along the axis, the occipital 
region is half, and the nasal two-tliirds, the extent of the orbital, which is very large. 
The “ tegmen cranii” covers two-thirds of the skull, and grows in well from the 
sides, so that the larger cordiform fontanelle is small, and the secondary spaces very 
minute. 
The parotic wings stand out well, and the canals ( a.s.ch.s.c., p.s.c .) are prominent. 
The ossification, right and left, is only equal that of the type, and the four normal 
centres ( pr.o ., e.o.) are separated by extensive tracts of cartilage. Above, the prootic 
stretches out in front so as to underlie the squamosal a little. Below, the floor of the 
vestibule ( au .) is unossified, for the ex-occipitals, which flank the posterior canal above, 
do not reach to the fenestra ovalis below. In front, the prootics just reach the optic 
fenestrse (II.). Of the remainder of the long orbital region the hinder half is unos¬ 
sified ; the rest, or the region of the “ girdle,” is partly ossified, and partly calcified, 
the latter tract marking out the usual extent of the bone, which however is only 
fully developed in front into an irregular |J -shaped bone, thick and rugged, but whose 
halves do not meet above (fig. 1 , eth.). In front, this imperfect girdle scarcely covers 
the proper ethmoidal territory, and the whole nasal region, and likewise the extensive 
superorbital crescents ( s.ob .), are unossified. Leaving these out, the form of the orbital 
region of the skull is oblong, modified by a slight bulging, and a gentle increase of 
breadth, forwards. 
The nasal territory ( al.n .) is large and four-square, with the roof spreading wider 
than the floor ; the septum (s.n.) is thick, and both above and below we can see clearly 
how much has been added to the original “ trabecular horns ” by the solid inter- 
trabecular wedge (or wall), and how much by the large shells of cartilage that form 
the roof. Their division also, into the floor (with its angles that bury themselves 
MDCCCLXXXI. 
X 
