DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
175 
Divergence from the “ norma ” is seen in :— 
1. The general breadth and depression of the skull. 
2. The thorough continuity of the endo-cranial bones of the hind skull, above, and 
of those of the same side, below. 
3. In the mid skull the great size of the optic fenestra, and the limited extent of 
the girdle-bone. 
4. The superorbital eave, and large single fontanelle. 
5. In the fore skull, the large, well made prenasal, and the unusual size of the pro- 
rhinals. 
6. The stylo-hyals and supra-stapedials are confluent, above. 
7. The fronto-parietals are arrested. 
8. The basal plate is very small, and the tliyro-hyals very large, 
48. Phyla albomarginata. —Adult female ; 2-g- inches long. Brazils. 
This species, which is nearly twice as large as those whose skulls have just been 
described, cannot be far removed from Phyllomedusa, in spite of its want of “parotoids.” 
Its skull is moderately strong in its outworks ; the endocranium very strong, although 
very flat; the ethmo-nasal region takes up half its length, and this causes it to be 
almost a long skull, the breadth being only one-Jiftieth greater than the length ; the 
jaw-hinge reaches very nearly as far back as the occipital condyles. 
Thus much of the divergence from the type is in this kind evident at first sight. 
Besides its likeness to the skull of the gigantic South American kind, it resembles 
very much that of an Australian sub-type, namely, Litoria marmorata (see Plate 19, 
figs. 11, 12 ; and Plate 32, figs. 6, 7) ; but the skull of that species is much less unlike 
the “ norma.” 
Even here the Ranine skull is but thinly veiled, and not so much metamorphosed 
in any part as to hide its fundamental character ; and yet this normal form is an 
acquired character, whilst the primary form was Petromyzine, or “ Suctorial.” 
The occipital condyles (Plate 32, figs. 6, 7, oc.c,) are small, subreniform, and postero- 
inferior ; they are separated by an interspace which is greater than their own width, 
and this is deep and crescentic ; the epiotic eminences (jo.s.c.) are nearly flush with 
them. 
A line drawn athwart the middle of the hind brain, and cutting the junction of the 
anterior with the posterior canals {ci.s.c., p.s.c.) would also run across the opening of 
the tympano-Eustachian cleft ( eu .), where the columella, pushes out its extra-stapedial 
process ( e.st .) ; this point is a little behind the middle of the drum of the ear ( a.ty .). 
The great parotic wings are half the breadth of the rather small proximal region of the 
auditory capsules ; they turn a little forwards, externally, but they are dilated somewhat 
along the tegminal margin (fig. 6, under sq.). 
The ossification of the hind skull is continuous everywhere, except a short oblong 
