250 MR. W. K. TARKER ON THE STRUCTURE AND 



The stylo-hyals are articulated (or partly confluent) with the ear-mass ; they are 

 narrow, but the cerato-hyal (fig. 4, c.Juj.) broadens up to the base, and the hypo-hyal 

 {h.hy.) has its lobe behind, and not in front, as is the rule. 



The basal plate is relatively rather small and long, the front lobe smallish and 

 rounded, the hind lobe normal ; the thyro-hyals {t.hy.) are large, and not so divergent 

 as in most kinds. 



The investinsr bones ai-e as remarkable as the endoskeletal, and the two kinds are 



o 



largely anchylosed together. The fronto-parietals (/i>.) form, together, an oblong 

 tract, largely confluent with the underlying bone, and not anchylosed together, except 

 behind, the fronto-sagittal suture bemg straight and nearly perfect. The two bones 

 are longest at the middle ; they form, in front, a low-angled projection ; they largely 

 overlap the endocranium, especially over the optic passages, where they are unusually 

 thick (fig. 3). The moderate temporal angle is ribbed, and where it rides over the 

 ear-mass, and coalesces with it, it is crenate, along a concave edge. 



From one double canal-arch to the other (fig. 1,/^^) the posterior parietal edge is 

 straight ; over the posterior canal the outlines are lost. I suspect that this part does 

 not cover any secondary fontanelles. 



The large, broad, conchoidal nasals (n.) are wide apart, and send down a short, blunt 

 facial process (fig. 3, /.p. by mistake) ; they cover a third of the cartilaginous snout; 

 as seen laterally, their edge is twice crescentically emarginate. 



The twin bones that finish the inferior and external facial arch (px.) are wider than 

 the rest of the arch, the maxillaries {mx.) soon narrowing in ; and the small quadrato- 

 jugals (q.j.), which simply articulate with the quadrate, are narrower still; there are 

 no teeth in the jaws. 



Both the nasal and palatine processes, as well as the body, of the premaxillaries. are 

 small and feeble; the contiguous part of the maxillary, on each side, is rather high 

 but does not reach the nasal at any point. The external nostrils, thrust out to the 

 sides of the wide muzzle, are, however, well protected (figs. 3 and G). The inner, 

 upper labial {u.l'^.) is larger than the premaxillary; it is semi-oval, with a dilated base; 

 it partly rests on the maxillary. The outer labial {u.l~.) is pedate below and rounded 

 above ; it lies outside and below the nostril, and equals in size the projecting part of 

 the roof (al.n.). 



Between the two labials there is a lozenge-shaped septo-maxillary (fig. 6, s.mx.), and 

 inside the outer labial there is a second larger bone — a pre-orbital (p.oh.). This bone 

 is two-thirds the size of the cartilage it is attached to, and of the same shape, but 

 reversed; it has its counterpart in Pipa (PhU. Trans., 187G, Plate 62). 



The squamosal (figs. 1, 3, and 7, sq.) is better developed than in Calluhi; it is 

 narrow, sigmoid above (fig. 1 ) ; is bent upon itself at less than a right angle ; and the 

 postorbital region of the upper part is hollowed out for the annulus and extra- 

 stapediaL and helps to increase the size of the tympanic cavity. 



This structure, which exists in some degree in most Anura, comes in tliis case very 



