PROSAURI RHYNCHOCEPHALI 



295 



only recent reptile which is devoid of them; a most primitive 

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

 other living reptiles. 



The supratemporal bridge is formed by the squamosal and 



Pmx 



Pmx 



Pig. 59.— a, Dorsal; B, ventral; C, left-sided view of the skull of Sphenoilmi. x #. 

 Ool, columella auris ; Cond, occipital condyle ; KP, ectopterygoid ; F, frontal ; Jiig, 

 ju^al ; Ma:r, maxillary ; jSTa, nasal ; JVo, auterior nasal opening ; Pal, palatme ; 

 'Par, parietal ; Pmx, premaxillary ; Prf, prefrontal ; Pt.f, postfroutal and post- 

 orbital ; Ptg, pterygoid or endopterygoid ; Q, quadrate and quadrato-jugal ; .S'^, 

 squamosal ; Vo, vomer. See also Fig. 54, B, p. 280. 



postorbital (Fig. 59, C, Ft.f), the latter being continued forwards 

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

 the ascending branch of the jugal, both together forming the 

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



