156 
MR, W. K. PARKER ON THE STRUCTURE AND 
above, they climb up to the inside of the posterior canal (fig. 6, p.s.c.), which they 
flank ; there they are wide apart. 
The prootic ( pr.o .) runs forward to the foramen ovale (V.), and outwards as far as 
to the tegmen tympani (fig. 6); they show mostly in front, and to a very moderate 
extent either above or below. Three-fifths of the orbital region is unossifiecl, and the 
optic fenestra (II.) in this type is larger than in the other (fig. 2). The girclle-bone 
( eth.) is more developed than in it, and it has ossified exactly all the cartilage that 
belongs to the ethmoidal region, for it has carefully avoided the anterior sphenoidal, the 
ethmo-palatine, and the true nasal, regions. The nasal region is very instructive; the 
proper roofs (fig. 6) are large cartilaginous pouches that have coalesced with the ethmoid 
behind, and with the large intertrabecula (nasal septum), ( s.n .) in the middle ; they even 
exaggerate the large size of the nasal region in the Polypedatidse, for they are very tumid, 
postero-laterally; a clean chink separates them from the ethmo-palatine bars ( e.pa.). 
In front, the septum grows out into a well-marked prenasal rostrum (figs. 6, 7, 9, 
p.n.). (In figs. 6 and 7, both this and the pro-rhinals ( p.rh .) are drawn as dissected 
out, and shown beyond the outer bones; they were examined by transmitted light.) 
The form of the larval cornua trabeculse is clearly seen below (fig. 7), as they first 
bend inwards at their first coalescence, and then spread out in front; their secondary 
cornua—the pro-rhinals (figs. 6, 7, 9, p.rh.) —are long, slender, and pedate. 
The secondary upper labials (u.l l .u.l 2 .) are well developed ; and the outer segment is 
an almost perfect “ annulus,” with an outer lip over the external nostril: this passage 
is far from its fellow, as in this “ Family ” generally ; three-fourths as far as the 
internal nostrils (i.n.), which, however, are very much larger than the outer. The 
facial “ bow ” is not so strongly bent as in the last, and here we have an arrested 
condition of the applied bony tracts {pa., pg.), which are extremely feeble, and like 
those of very newly curtailed Common Frogs. The cartilaginous palato-suspensorial 
bar is well developed ; the pedicle ( pd.) is large, and the quadrate region (q.c.) is thick, 
and of the normal length. The condyles, however, are very peculiar; they are 
obliquely saddle-shaped, and have not the usual resemblance to a kidney. 
But one of the rarest characters, for an adult, turns up here : this is the retained 
orbitar process [or.p.), a structure which is large in the Tadpole, in all the Anura, and 
is to be seen in Polyodon (see Bridge, Phil. Trans., 1878, Plate 57, or.p.); I find it 
also in the Sturgeon. 
It remains here as a round leafy lobe {or.p.), at the point where the quadrato-jugal 
and squamosal {q.j., sq.) meet. 
The Eustachian tubes are large and reniform ; they turn outwards and a little 
forwards. The annulus {a.ty.) is rather small, and does not unite above ; the stylo- 
hyals {st.h.), coalesce with the auditory capsule. The stapes (fig. 10, st.) is large and 
oval ; the inter-stapedial {i.st.) is large and semi-osseous : the medio-stapedial {m.st.) 
is a pistol-shaped rod of bone, which ends in a tongue-shaped cartilage, the extra- 
stapedial {e.st. ); it has no ascending process. 
