580 



REPTILES. 



Fig. 252. — Skull of grass snake. — From W. K. Parker. 



A Dorsal surface— fix., premaxilla; nix., maxilla; an., external nostril; «., nasal; oi., 

 nasal cartilages ; pf., prefron to-lachrymal ; p., parietal ; /., frontal ; pa., palatine ; 

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

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

 d., dentary ; g., quadrate ; sg., squamosal. B, Ventral surface—; fx. , premaxilla; ol., 

 nasal cartilage ; mx. , maxilla ; z\, vomer ',pa., palatine ; p., parasphenoid ;/., frontal ; 

 Pf., prefrontal \pg. , pterygoid ; bs. , basisphenoid ; als. , alisphenoid ; 6.0. , basioccipital ; 

 oc.c, occipital condyle ; eo., exoccipital; g., quadrate ; ar., articular ; ag., angular; 

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



