THE LIMBS OF AMPHIBIA. 



179 



outer margins of tlie posterior nares, and then extend back 

 on tlie inner side of the maxilla, in a manner irnlike any- 

 thing observed among other existing Amphibia. But in the 

 Labyrinthodonta, both this disposition of the palatine and 

 the complete roofing over of the skull by bone are repeated, 

 and there is a postorbital bone. 



Fig. 56. 



Frnx. 



Fig. 56. — Side and iipper views of the skull of Trematosavrus. The 

 sculpture of the cranial bones is not represented in the lower half 

 of the upper view of the skull, in order to show the sutures more 

 distinctly. 



The Labyrinthodont skull is further characterised by the 

 development of distinct pointed epiotics, like those of 

 fishes, and of paired ossifications, which take the place of 

 the sxipra-occipital, as in many Ganoidei. In many Labyrin- 



