]3HVKr,0PMKXT OF THE SKTLL IX THE BATRACHIA. 193 



They then become narrow bands, and in front turn outwards, over the superorbital, 

 which they partly cover ; their end is truncated. By this divergence the girdle-bone 

 is left naked, and the fontanelle is scarcely covered at all by them. 



The nasals (n.) are rather small shells; they have a falcate outline, and are notched, 

 behind ; the hollow blade overlies the very limited nasal roof. The marginal bones 

 are well developed; the nasal process of the pi'emaxillary (px.) is thick, wide, and 

 high ; it is capped by tlie small 1st labial. 



The maxillary (ma:;.) is veiy high in front, and i-ather high behind; where it shelves 

 downwards, over the premaxillary there is a small, notched septo-maxillary (s.nix.); 

 the qiiadrato-jugal (qj-) is normal in size ; it is largely continuous with the quad- 

 rate (q.). 



The squamosal (sq.) lias a long falcate upper part, and a long, broad, retreating 

 lower part. 



The parasphenoid (figs. 2, 3, prt.s.) is large, smootlily convex below, and has all its 

 four rays pointed. 



The vomers (fig. 2, v.) are at their highest development ; they occupy all but the 

 fore margin of the very wide subnasal cartilage, and as the large circular inner 

 nostrils (^.n.) are wide apart, there is a large inter-narial space for the two vomers, 

 which fit, by "harmony," along the mid-line. 



Each bone sends a narrow sharp snag out in front of the passage, and in front of 

 this a broader falcate process. 



But each bone has a large oblong body, with a rounded front, and a nearly straight 

 hind, margin ; this part is thickened into a smooth, rounded mass, whose hind margin 

 bristles with retral teeth. 



This tootlied lobe projects a little further backwards on the outer, than on the inner, 

 edge. 



At fii'st sight it would seem dlfiicult to make out many points of difterence between 

 this skuU and that of the two European species of the typical Frog (Raim), for the 

 size is intermediate between the two, and the elements are essentially the same in this 

 and in them. 



Nor are the relative proportions of the three regions of the skuU different in any 

 remarkable degree ; nor the proportionate quantity of bone to be found in the endo- 

 cranium. 



Carefully compared with the t^^ie, this skull is seen to differ in the following 

 respects, namely: — 



1. There is a very distinct post-auditory arch. 



2. The parotic wings are of great extent, and give off a long " pterotic " process 

 postero-externally. 



3. Each lateral mass of bone has lost all signs of division, above. 



4. The mid skuU is very fiat, has wide tegminal margins, and has one moderate 

 fontanelle. 



MDCCCLXXXT. 2 C 



