38 
MR. W. K. PARKER ON THE STRUCTURE AND 
respects it corresponds with the Oriental Frogs, and differs from most of those of the 
Nearctic and Palsearctic regions; this is seen in the presence of an “ anterior super¬ 
orbital ” expansion of the chondrocranium (Plate 5, fig. 1). 
This is an unusually narrow and elongated skull, and thus differs from that ot 
JR, pipiens which is short and wide ; the last was elongated but did not narrow in so 
much in front. This sub-triangular form, the relatively elongated nasal region, and the 
gradual, but great, widening from before backwards of the cranial “ barge,” are very 
characteristic things in the skull of this species. Add to these the rudimentary super¬ 
orbital plate in front at the narrow end of the skull, the wide temporal region, the 
heart shaped great fontanelle, and the small lesser fontanelles, and we get a number oi 
things worth notice. Yet these are of secondary morphological importance, their value 
is largely Zoological and Taxonomic. In the nasal region we see that the outer angle of 
the “subnasal” cartilage ( s.n.l .) has formed a retral lobe—a part very distinct in the 
adult R. temporaria. The pro-rhinals ( p.rh.) are rather retral than out-turned; the 
upper and lower cartilaginous laminae are curiously alternated as to their wide and 
narrow ends; the upper is narrow in front, and the lower wide, and vice versa. 
The bending of the palato-pterygoid “ bow ” is greater here than in the last, and 
the proper suspensorium is modified by the more backward position of the quadrate 
condyle (q.c.), by the fusion of the otic process with the “ tegmen tympani ” (fig. 1, 
between the letters a.s.c. and h.s.c.), and the greater perfectness of the articular facet 
of the pedicle ( pd.). 
The ex-occipitals (e.o.) are now large, and leave only a narrow oblong basioccipital 
space, and a wider triangular superoccipital tract of cartilage; they have risen over 
their own roof, and up the inside of the “ epiotic ” region, partly walling in the 
posterior canal (p.s.c.). 
The prooties ( pr.o.) are now typical, they enclose the great foramen ovale (Y.) for its 
outer half below, and run round the front from thence, above; further out they have 
climbed up on to the auditory capsule, flanking the anterior canal on its outside, and 
covering the ampulla of the horizontal canal (a.s.c., h.s.c.). 
A pair of “ sphenethmoidal ” centres have appeared in the chondrocranium under 
the superorbital cave, and behind the ethmo-palatine bar ( e.pa.) ; these are the 
symmetrical rudiments of the “girdle-bone;” they are “ ecto-ethmoids” now, and are 
the proper side-wall bones ^protecting their own nerves (the 1st), just like the prootics 
of the Frog, the alisphenoids of Teleostei and higher types, the orbito-sphenoids of 
many types, and the ex-occipitals here and everywhere. They are separated by a tract 
equal to their own width below.* 
* There is much variety in the formation of the girclle-bone, but these are its most essential parts; it 
may have, however, a median element below (as in Pseudophryne Bibronii), or an azygous plate above 
(Bana temporaria, Bappia ( Hyperolius ) bicolor). In Bactylethra (“ Batrachian Skull,” Part 2, Plate 59, 
fig. 1 , s.etli.) this is a large "J" -shaped bone, it is free from the cartilage below it, which is not ossified so 
far forwards. 
