230 
MR. W. K. PARKER ON THE STRUCTURE AND 
Third Family. “ Brachyceph altd/E. ” 
Ear very imperfect; no parotoids ; sacrum dilated. 
Genus Pseudophryne. 
67. Pseudophryne Bibronii. —Adult female, 1 inch long ; and adult male, § inch long’. 
New South Wales. 
The skull of this Bombinator Toad is another example of arrested metamorphosis 
combined with relapse, so to speak, into general vertebrate characters that are, 
normally, suppressed in the Anura. 
Whether what we see in skulls like this is due to relapse, or the retention of more or 
less unchanged, old, ichthyic, pro-Batrachian characters, the interest of the matter is 
equal, for the transforming power which has wrought so mightily in the higher kinds 
to set them on high above the fishy tribes, generally, has in these southern dwarfs 
found some check, or has never, as yet, come into full play. 
The length and the breadth of this little skull are equal (Plate 42, figs. 1, 2), and 
up to the hinges of the mandible the outline is a neat semi-ellipse; but these hinges 
are only opposite the scarcely open Eustachian cleft (eu.). Instead of getting some 
distance behind the small occipital condyles, as in some types, the condyles of the 
quadrate (pc.) only reach along two-thirds of the length of the skull. The arrest, 
generally, corresponds with what has been done in typical kinds by the time the tail 
is u T ell absorbed, or at most up to the first summer. 
The three regions of the skull are about equal in length, and the auditory capsules 
are relatively very large, obliquely oval, with prominent canals (a.s.c., h.s.c., p.s.c.); 
and the parotic outgrowth is nothing but the small unossified selvedge which forms the 
tegmen ( t.ty .). The occipital ring is very distinct and protruding, but the foramen 
magnum (fig. 1) is very oblique, and open above. The ossification on each side is 
generalised, for there is no distinction of prootic and ex-occipital (au., vb., e.o.), and yet 
it is very complete, except at the edge and the middle, above and below. There we 
see the cartilage is wide and widening; above (fig. 1), it runs forwards to the fore-third 
of the hind skull, and ends in a peak which converts the large, single fontanelle into 
a heart-shaped space. 
Below (figs. 2 and VII., b.o., nc.), the permanent cephalic notochord is covered 
with bone (a “ cephalostyle ”), and this bony matter has run into the investing mass, 
right and left, so that here we have a true, but arrested, “ basi-occipital ” bone. 
The broad, short mid skull lessens quickly up to the ethmoidal alee; it is rounded, 
or swelling as in young Anura. The bone scarcely reaches the foramina ovalia (V.), 
which are large, and two-thirds of the orbital wall remains unossified. Nearly half 
that space is occupied by the large oval fenestra optica (II.), through the back part of 
which the optic nerve escapes. At the fore edge of this space we have a bony tract 
