9 o 



COMPARATIVE MORPHOLOGY OF VERTEBRATES. 



FIG. 91. Skull of Plesiosaurus macrocephalus, after Andrews, ang, angulare; art, 

 articulare; ch, choana;/r, frontal; orb, orbit; pa, parietal; pal, palatine; pas, parasphenoid; 

 po+pof, postorbital and postf rental; sf, supratemporal fossa; t, transversum. Other 

 letters as in fig. 68. 



m x 



FIG. 92. Dorsal and ventral views of the skull of turtle, Trionyx ss, exoccipital; 

 m, maxillary; p, (behind naris), preorbital; pno, postorbital; s, supraoccipital; other 

 letters as in fig. 68. 



