446 



Comparative Morphology of Chordates 



Olfactory capsule 

 Sphenethmoid 

 Fontanels 

 Primary upper jaw 

 palato-- 

 pterygo- 

 quadrate— . 

 (suspensonum)\ 



Ouadratojugal 



Premaxilla 

 Vomer 

 Nasal 

 Maxilla 

 Frontoparietal 

 Squamosal paraquadrate 

 Ouadratojugal 



Fig. 3 l">. Skeleton of frog (Rana calesbiana): dorsal view except that the feet are 

 extended backward so that they are seen in ventral aspect. In the skull most of the 

 dermal bones of the left side have been removed (the quadratojugal remaining), 

 together with a narrow strip of the right frontoparietal, so as to expose the chondro- 

 cranium and the primary cartilaginous upper jaw (palato-pterygo-quadrate) con- 

 tinuous with the cartilaginous olfactory capsule in front and the auditory (otic) 



