DEVELOPMENT OF THE SKULL IN THE BATRACHLA.. . 101 



bend inwards in front of their fork, and the inner process covers tlie 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 {eu.) are large and circular ; the annulus (fig. 5) is small 

 — two-thii'ds the typical size— and imperfect above. The stapes (figs. G and 8, st.) is 

 large, oval, only straight-sided snpero-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 roedio-stapedial bone {m..st.) is dilated at the upper 

 end, where it fails to ossify the bilobate ti-act ; 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 pi'ocess. The stylo-hyal 

 end of the hyoid (fig. 8, st.h.) is narrow, and articulates with the auditory floor. 



The mandibles (fig. 7) are long, and quite normal ; the mento-Meckelian part 

 {m.mk.) is unusually large, showing that the lower labial kept fts size, after fusion 

 with the mandible, more than is the case generally. 



The hyo-brancKial 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 thyro-hyals {t.hy.) are very .slender, diverging rods. 



The investing bones (figs. 5 and G) show a feeble skull ; the fronto-parietals (fig. 5, 

 f.p.) 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 roiuid lobe ; these lobes, right 

 and left, cover much of the unossified supraoccipital tract {t.cv.) ; externally, each bone 

 just rises on to the swelling of the anterior ampulla {ct.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, fci.s.) is typical, but very broad iti the main shaft, and 

 notched in front ; the vomers {v.), as in Fleurodema (fig. 2), are placed almost trans- 

 versely, and the inner nostrils (in.) open wide apart in the large rounded notch of 

 each vomer. The main wing of the bone, m 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 ; 

 their 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 premaxillaries 

 {px.) are wide, and the septo-maxillarles (s.nix.) small ; they lie outside the second 

 upper labial ; both these cartilages («./'. m.Z'.) are normal. The squamosals (*</.) are 

 slight, and only just clamp the edge of the short tegmen tympani {t.fi/.); the 



