DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
99 
5. The palatine ectostoses are in two pieces on each side. 
G. The quadrate is partly ossified. 
7. There is no distinct inter-stapedial. 
8. The supra-stapedial is confluent, above. 
Filth genus. Lymnodynastes. 
23. Lymnodynastes tasmaniensis .—Adult female ; If inch long. Tasmania. 
This is a long skull (Plate 18, figs. 5-8), with short auditory, long nasal, and 
average orbital, regions. The length is the fortieth of an inch greater than the 
breadth, and the outline of the face is half a long oval. The sides are rather straight 
in the jugal region, for the broad and long nasal region makes the fore edge a regular 
semicircle. The whole ethmo-nasal territory is, as compared to the skull cavity, as 
2 to 3 in length; the average fore and aft extent of that territory, as compared 
with that of the cranium proper, is as 1 to 2. The occipital condyles ( oc.c .) are of 
moderate size, and of the usual distance from each other; they project but little, are 
more posterior than inferior, and the emargination of both floor and roof is crescentic. 
The auditory capsules are of moderate size and become narrow at the tegmen ( t.ty .); 
the cranial interspace between them is very wide, especially in front. 
The ethmoidal region ( eth .) is also wide, and the broad flat skull is almost like an 
hourglass, being much the smallest in the middle, and thus the snborbital fenestra: 
are almost oval in shape, the arcuate palato-pterygoicls bounding them externally. The 
whole pre-cranial region is very flat and outspread. 
The tegmen cranii ( t.cr .) is more complete in this skull than in most of those known 
to me; it resembles in this respect the skull of the Skate, the roof growing along from 
the sides, so as to leave, when the roof-bones are removed, a space little more than 
a third as wide as the narrow interorbital region, and little more than a third the 
length of the cranial cavity. 
Also those secondary spaces, so characteristic of the Anura,, are absent, and the wide 
inter-auditory space, above, is completely chondrified. The tract, moreover, in front of 
the fontanelle (etli.) is large both ways, so that a very unusual amount of the girdle- 
bone is exposed. The ex-occipitals and prootics ( e.o ., pr.o.) are confluent for some 
extent at their inner edge, above ; below, there is a good space of cartilage dividing 
them. Above (fig. 5), the whole tegmen tympani (t.ty.) is soft, and a w r edge-shaped 
tract of cartilage is seen between the bones. Behind this tract the ex-occipital is seen to 
reach outwards beyond the horizontal canal ( h.s.c .) and inwards to such a distance from 
the middle that the superoccipital region (fig. 5) is left of unusual width. Below, the 
basioccipital synchondrosis (fig. 6) is only half that width, and is quite normal. 
The prootics run forwards, above (fig. 5, pr.o.), over the optic passage, and inwards 
o 2 
