170 PEOF. W. K. PAEKEE ON THE MOEPHOLOGY 



beyond the apices of the pterygoids as far as in an average Batrachian : there is, however, 

 no quadrato-jngal to bind them to the quadrate ; they are free as in Osseous Fishes. The 

 dentigerous line, continuous in front with that of the premaxillaries (fig. 2), extends 

 nearly to the distal end. Above, at tbe junction of these bones, and outside the external 

 nostril (e.n), there is a small graniform septo-maxillary (figs. 1 & 3, s.mx). The squa- 

 mosals (figs. 1 & 3, sq) have a convex, suboval supratemporal region (fig. 1), and a large 

 oblong preopercular part (fig. 3) ; above, they lie over the two first ampullae and the 

 tegmen tympani, whilst the descending part strongly binds upon the outer face of the 

 suspensorium. After being broad above, and narrowing somewhat down the shaft, the 

 bone has a broad arcuate base fitting against the expansion of the quadrate, towards the 

 condyle. 



Over the nasal region there are two pairs of bones on each side ; the nasals (n) are the 

 inner, and the ectethmoid plates (e.eth) the outer of these. The nasals have an anterior 

 margin, which is concave, to fit against the external nostril (e.n) ; their main part is 

 wedged in between the nasal processes of the premaxillaries, the ascending plate of the 

 maxillaries, and the ectethmoids ; their hinder angle rests upon their frontals. 



These latter bones (e.eth) are oblong ; they form, as it were, two horns to the pair of 

 frontals (f), stretching outwards and forwards ; the orbito-nasal nerve (5 1 ) passes into the 

 olfactory sac between their outer end and the high part of the maxillary. These bones 

 remain distinct. Taken together, the frontals and parietals (fig. l,f,p) have an hour- 

 glass-shaped outline ; this figure is made up of four nearly equal bones. 



In front, the frontals are overlapped by the nasals, nasal processes of the premaxillaries, 

 and ectethmoids ; behind, they repeat this imbrication by lying on the parietals, towards 

 which they narrow, whilst towards them the parietals are narrowed. The superorbital 

 margin (figs. 1 & 3) is strong, but not overarching ; there the parietal runs forward, 

 coping the cranial wall. 



Behind, the parietals are trilobate ; the first or outer lobe binds on the front of the 

 ear-mass; the middle lobe covers the junction of the anterior and posterior canals; the 

 third or inner lobe meets its fellow over the supraoccipital region, tiling that roof nearly 

 to the edge of the foramen magnum. 



The great parasphenoid (figs. 2, 3, 5,pa.s) has its narrow anterior part invested by the 

 vomers, and its middle region by the long palatines ; behind, it is wide, and rendered 

 irregularly crenate by four pairs of notches; there are three denticulations on this 

 foliaceous part. 



The inferior arches now come under review. The first of these is the free mandible ; 

 this is now a flat arcuate bar, well ossified by the long sheathing articulare (figs. 3 & 5, 

 ar), which has ossified nearly all the cartilage except the oblong cylindroidal condyle. 

 The articulare reaches far forwards, but is encased in two splints ; in front of the 

 condyle it sends upwards a coronoid process. The external dentigerous splint, the 

 dentary (d), reaches from the chin to the angle of the jaw, and ends only slightly in front 

 of the end of the articulare. On the inside it lies over the edges of the jaw, but is 

 deficient in the middle. This deficiency is made up by a long curved dentigerous 

 lath, the splenial (fig. 5, sj)) ; the bone is pointed at both ends, and reaches from the 



