DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 113 



much less typical, and some of them are very aberrant and generalised. Hence it 

 comes to pass that this is rather a motley group, and the question arises as to whether 

 it should not be broken up and i-edistributed ; if this were done the boundaries of the 

 groups that should receive their own relations back again, would have to be made 

 more elastic. This type w-ould have to go to the Ranidae ; Calyptocephalus to the 

 Cystignathidae ; Pelodytes would ask for admittance, either among the Bombinatoridae, 

 or the Alytidse ; whilst Xenophvys, and the kinds agreeing with it, would probably 

 have to be made into a new family ; that species is exceedingly generali.sed, and shows 

 affinity wnth families far removed from the Ranidee, far more clearly than with those 

 typical Frogs. My mention of these things is as a protest against the family group 

 as it now stands : the Zoologists must re-arrange it as they see fit. 



As far as the skull is concerned, this type might have been left in the genus liana, 

 or still better, put with the species of Pyxicephalus ; with that of F. ru/escens it agrees 

 very closely. This is a typical semi-elliptical skull, whose breadth is to the length as 

 15 to 14 ; it is more fraU, or less ossified, than in the avei'age Frog's skull ; and its roof 

 is imperfectly covered. 



The extent of the three regions of the skull is normal, the orbital being the largest, 

 the nasal next, and the auditory the shortest. The occipital condyles (Plate 20, 

 figs. 7, 8, OCX.) are large, semi-oval, almost directly posterior, and separated by a 

 narrow notch. 



The epiotic projections (p.s.c.) are gently convex, and come short, behind, of the 

 condyles. The quadrate hinges are opposite the large twin nerve-passage (q.c, IX. X.). 

 The small ex-occipitals (e.o.) are wide apart both above and below, and are at a con- 

 siderable distance from the equally arrested prootics (pr.o.); these latter bones enclose 

 the foramina ovalia (V.), run out to the facet for the pedicle (pd.), and up over the 

 anterior canal (a.s.c). Beyond these bones the tegminal region (fig. 7) is only half the 

 width of the canal region, and runs only a moderate distance beyond the horizontal 

 canal {h.s.c). The skull is well roofed, for the main fontanelle (fo.) is a rather small, 

 long, heart-shaped space, and the small secondary fontaiielles are wide apart on the 

 large hinder part of the tegmen cranii. 



The temporal region is wide, and from thence the orbital part of the skull narrows 

 up to the rudimentary superorbital projections (f.ob.) ; these increase the width a little in 

 the ethmoidal region, but, as in Pyxicephalus ru/escens (Plate 14, figs. 1, 2), the cranial 

 boat is very constricted in front. As in some small Eanidte from Australia {e.g., 

 CamarioUus), the girdle-bone (eth.) is imperfect ; it occupies only about a fourth of the 

 iuterorbltal region at its widest ; its halves are united by a narrow isthnms below, and 

 scarcely meet above. 



Most of the ethmoidal region, with its wings, and all the wide, well-developed, 

 normal nasal region, are cartilaginous. Both roof and floor (figs. 7, 8) are wide, 

 the septum (s.h.) is high and thick, the snout gently convex, with a shght prenasal 

 bud; and the pro-rhinuls (p.rh.) and subna.sal outer angles are large and well 



MDCCCL.XXXI. Q 



