DEVELOPMENT OF THE SKULL IN THE BATRACHIA 
101 
bend inwards in front of their fork, and the inner process covers the short cartilaginous 
“ pedicle ” very imperfectly. The quadrate region (q.c.) is short, but the condyle is 
large and reniform; it only reaches to the middle of the columella ; this region is not 
ossified. The Eustachian tubes (su.'j are large and circular; the annulus (fig- 5) is small 
_two-thirds the typical size—and imperfect above. The stapes (figs. 6 and 8, st.) is 
large, oval, only straight-sided supero-anteriorly, not emarginate ; for the columella is 
very small (fig. 8); it is pistol-shaped, has a bilobate unossified tract fitting inside the 
stapes, but no segment there. The medio-stapedial bone ( m.st .) is dilated at the upper 
end, where it fails to ossify the bilobate tract ; it then becomes a very slender rod, 
dilating gradually to its end, beyond which the unossified distal part is a small, 
narrow, cochleate extra-stapedial (e.st.), with no ascending process. The stylo-hyal 
end of the hyoid (fig. 8, st.ln .) is narrow, and articulates with the auditory floor. 
The mandibles (fig. 7) are long, and quite normal; the mento-Meckelian part 
(' in.mk .) is unusually large, showing that the lower labial kept its size, after fusion 
with the mandible, more than is the case generally. 
The hyo-branchial plate (fig. 7) is normal, the basal part is wide, but its processes 
are slender ; the hypo-hyal lobe (h.hy.) is sharp and slightly perforate ; the lateral lobes 
are smaller than usual, and the tliyro-hyals (t.hy.) are very slender, diverging rods. 
The investing bones (figs. 5 and 6) show a feeble skull; the fronto-parietals (fig. 5, 
fjp.) are thin curved shells of bone, hooked outwards, in front, where they bind on the 
outer angle of the girdle-bone, sinuous along their inner edge, where they form a waist 
to the fontanelle (fo ), and dilated behind into a large round lobe ; these lobes, right 
and left, cover much of the unossified supraoccipital tract (t.cr.) ; externally, each bone 
just rises on to the swelling of the anterior ampulla ( a.s.c .). 
The nasals (fig. 5, n.) are large, but leave a width of cartilage uncovered between 
them, equal to their own diameter. These bony shells are notched behind the outer 
nostril, in relation to it; their postero-external part, or handle, is short and sigmoid. 
The parasphenoid (fig. 6, pa.s.) is typical, but very broad in the main shaft, and 
notched in front ; the vomers ( v .), as in Pleuroderna (fig. 2), are placed almost trans¬ 
versely, and the inner nostrils (i.n.) open wide apart in the large rounded notch of 
each vomer. The main wing of the bone, in front of that notch, is, as usual, split into 
two sharp lobes. The dentigerous stem of each bone is a long thick rib, serrate with 
recurved teeth, subcrescentic in outline, and nearly reaching its fellow. Hence in 
opening the mouth of a Frog of this species the vomerine teeth are seen to run nearly 
straight across behind the inner nostrils, and to be scarcely separated at the middle ; 
then real direction is inwards, and a little backwards, their ends lying under the fore 
margin of the girdle-bone. 
The bones that fence the semi-oval face are normal, but delicate ; the premax diaries 
(; px .) are wide, and the septo-maxillaries ( s.mx .) small ; they lie outside the second 
upper labial; both these cartilages ( u.V-.u.l 3 .) are normal. The squamosals (sq.) are 
slight, and only just clamp the edge of the short tegmen tympani (t.ty.); the 
