Fig. 54. — Diagrams of skulls, showing especially the composition of the bony arches nf 

 the orbito-temjioral region. 



A, C, D, E, Theromorpha. A, Elginia, p. 305 ; C, Cynognathus, p. 306 ; D, 

 Gordonia, p. 310 ; E, IHcynodon, p. 310. 



B, G, Prosauria. B, SiJhetiodon, p. 294 ; G, FalaeohaUeria, p. 291. 

 F, Crocodilia, p. 434. 



H, I, K, Chelonia, p. 316. H, Chelydra, p. 338 ; I, Chrysemys, p. 346 ; K, 

 Cistudo, p. 361. 



U, Epiotic ; F, frontal ; JT, infratemporal fossa ; ■/, jugal, shaded vertically ; 

 L, lacrymal ; Af, maxillary ; JV, nasal groove ; JVa, nasal bone ; 0, orbit ; 

 P, parietal ; Po, postorbital, dotted ; Pf, post-frontal ; Pjn, premaxillary ; 

 Pr, prefrontal ; Ptg, pterygoid ; Q, quadrate ; Qj, quadrato-jugal ; So, supra- 

 occipital ; Sq, squamosal, shaded obliquely ; St (in B-E), supratemporal fossa ; 

 St (in A), Supratemporal bone. 



