708 



PHYLUM CHORDATA : CLASS REPTlLtA 



iHX 



Fig. 418. — Skull of grass-snake. — From W. K. I'arker. 



Dorsal surface — px., preniaxilla ; mx., maxilla ; an., external nostril ; n., nasal ; 0/., 

 nasal cartilages ; pf., prefronto-lacln-ynial ; p., parietal ; /., frontal ; pa., palatine ; 

 t.pa., transpalatine ; pg., pterygoid ; pro., pro-otic ; ep., epiotic ; op., opisthotic ; 

 so., supraoccipital; eo., exoccipital ; ar., articular ; s.ag., surangular; ag., angular ; 

 (i. dentary ; ^., quadrate; s^., squamosal. B, Ventral surface — />;<;., premaxilla ; ol., 

 nasal cartilage ; mx., maxilla ; v., vomer ; pa., palatine ; p., parasphenoid ; /., frontal ; 

 pf., prefrontal ; pg., pterygoid ; 6s.,basisphenoid ; als., alisphenoid ; b.o., basioccipital; 

 oc'c, occipital condyle \ eo., exoccipital ; q., quadrate ; ar., articular ; ag., angular ; 

 s.ag., surangular ; cr., coronary ; sp., splenial ; d., dentary ; op., opisthotic region. 



