15G JIR. w. K. PARKER OX THE STRUCTURE AND 



above, they climb up to the inside of the posterior canal (fig. 6, p..v.c.), which they 

 flank ; there they are wide apart. 



The prootic (j^i'.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 iniossified, and the 

 optic fenestra (II.) in this type is larger than in the other (fig. 2). The girdle-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 sjihenoidal, the 

 ethmo-jmlatine, 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, 

 ]y.n.). (In figs. 6 and 7, both this and the pro-rhinals {p.rh.) are drawTi as dissected 

 out, and shown beyond the outer bones ; they were examined by transuntted light.) 



The form of the larval cornua trabecidse 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 (i(,.l^.u.l~.) 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 (^a., pg.), which are extremely feeble, and like 

 those of very newly curtailed Common Frogs. The cartilaginous palato-suspeusorial 

 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 Sturo;eon. 



It remains here as a i-ound 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.tij.) 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 (hi..s<.) 

 is a pistol-shaped rod of bone, which ends in a tongue-shaped cartilage, the extra- 

 stapedial (est.) ; it has no ascending process. 



