DKVKI.OPMENT OF THE SKULL IN THE BATRACHIA. 235 



The want of symmetry mentioned above is best seen in tlie roof-bones (fig. l,f.p., n.). 

 Large as are the fronto-parietals, they barely cover the two lesser fontanelles, behind, 

 and there is an open chink in front. In their hind third they are anchylosed ; their 

 angular postorbital projections are not opposite, the left is in front of the right, and 

 their jagged fore part shows the same asymmetry ; their orbital edge is sharp and 

 separated from the rest by a sub-marginal fossa ; there is a good space between these 

 bones and the nasals, leaving the girdle-bone naked : the orbital plate (fig. 3, f.}i.) is 

 definite, but narrow, less than a third the depth of the shallow skull-basin. The left 

 nasal {n.) does not go so far back or so far inwards as the right ; it is only three-fourths 

 the size of the latter ; contrary to rule, the nasal, broadening outside, lies right down 

 on the top of the maxillary (fig. 3, n., mx.), leaving only a little chink in front. The 

 nasals are (relatively) thick, convex shells ; they are not entirely free from the 

 subjacent endoskeletal bone (eth.). They are round in front, a good space apart, and 

 leave the Anatine snout uncovered. 



The premaxillaries (px.) run across under the snout, and meet at a large angle; 

 they have pointed palatine processes (fig. 2), and short, tilted nasal processes (fig. 3). 



The maxdlaries (mx.) are of the average size, and only become pointed near their 

 end ; their sharp edge has a narrow palatine plate growing from it (fig. 2). 



The quadrato-jugals (qj.) are small, short, curved bones, slightly connected with 

 the suspensorium (q.), and only touching the end of the maxillary. The squamosals 

 {sq.) are in this species very instructive ; they might be described as " preoperculars," 

 bent the wrong ivcvj : a thing not impossible, for the outer bony plates are brought 

 under the power of the endocranium to a very remai'kable extent, and " without 

 hands," are moulded upon it, cunningly. 



In tliis species the supratemporal part of the bone is very naiTOW, and only clamps 

 the edge of the unossified "tegmen," {t.tn.) ; Moreover, the axis of the supratemporal 

 region is coincident with that of the stunted postoi^bital ; the short descending part 

 bends itself backwards at a very obtuse angle ; this is the rounded space against, and 

 partly on which, the small " annulus " (ci.ty.) lies. 



The parasphenoid (fig. 2, pa.s.) is a very remai-kable bone, it is almost all " wings ; " 

 measured to the mid-line they are larger than the scoop-like fore part ; they ai-e also 

 broader, and are obliquely truncate outside. Between these wings thei'e is a fore- 

 looking, triangular spur, as large as the hinder projection of the bone. The bone falls 

 far short of the middle part of the ethmoid, in front. 



The latter bone {eth.), in its subnasal extension, shows two sigmoid crests that 

 boimd the widely severed internal nostrils {i.n.); these are the anchylosed vomers (v.); 

 the right is much larger than the hft. 



I shall compare the skuU of the three species of this genus with that of the " norma," 

 together ; they differ remarkably inter se ; but agree with each other in being almost 

 the most abnormal of all the tongue-hearing Anura. 



■J. IJ 2 



