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TEXTBOOK OF ZOOLOGY 



are the premaxillaries, maxillaries, nasals, frontoparietals, quadrato- 

 jugals, squamosals, parasplienoids, and vomers. The bones enclosing 

 the brain constitute the cranium. 



On the dorsal surface of the cranium, the two frontoparietals 

 form most of the roof, the pro-otics form the roof of the auditory 



— PrzmaxlUary 



Moxi//ary 



-— -v-%— 5phenethmo(d 



^— Frorko-par\eba\ 



■J- Pterygoid 

 - - Squamosal 

 -\\— Pro otic 

 I- Squamosal 



—Quadratojuqal 

 Columella 

 Fig. 279. — Dorsal view of the skull and upper jaw of the bullfrog. 



- Premaxillary 



— Palatine 



fronto-parietal 



y^- Parasphenoid 



-Squamosal 



'^ -Quadrabjugal 



-Quadrate car- 

 ' $. tilaqe 



Fig. 280. — Ventral view of the skull and upper jaw of the bullfrog. 



capsule (inner ear capsule), the sphenethmoids form the posterior 

 wall of the olfactory capsule (nasal chamber), and the two tri- 

 angular nasal bones lie above. On the ventral surface of the era- 



