VIII 



I'ROSAURI — RIIVNCHOCErilAIJ 



295 



only recent reptile whicli is devoid of tlicm ; a most primitive 

 condition, sufficient Ity itself to separate this creature from all the 

 other living reptiles. 



The supratemporal bridge is formed by the s(|uamosal and 



Pttik 



Pm\ 



Fifi. r>9. — A, Dorsal ; B, ventral ; C, lett-sided view of the skull of Spheiiodnn. x i|. 

 Col, columella anris ; ('(duI, occipital eoiidyle ; E.P, eetopterygoid ; F. frontal ; Jng, 

 j'ucral ; Max, maxillary ; A'«, nasal ; K<u anterior nasal opening ; J'nl, jialatine ; 

 I'ar, parietal ; J'mx, ])remaxillary ; I'rf, prefrontal ; Pt.f, postfrontal and post- 

 orbital ; Ptg, pterygoid or endopterygoid ; Q, quadrate and qiiadrato-jugal ; Sq, 

 squamosal ; Vo, vomer. See also Fig. .")4, B, ]>. 280. 



postorbital (Fig. 59, il, Pt.f), tlie latter being continued forwards 

 and fused with the postfrontal (A, Pt.f). The postorbital joins 

 the ascendin" brancli of the iu'^al, both toL^ether formim;' the 

 hinder border of tlie orbit ; this is bordered below chiefly by 



