240 



EEPTILIA 



CLASR III 



Trachodon, Leidy (Radrosaurus, Thespesius, Leidy ; Diclonius, Cope), (Figs. 

 343-345). Skull elongated, depressed, with broad, beak-like siiout, very large 



Pnix: 



art 



aug- 



Prd 



Fig. 343. 



Trachodon mirahilis, Leidy. Uppermost Cretaceous (Laramie Formation); Dakota. Superior and lateral 

 aspects of skull, 1/12. A, Orbit; ang, Angular; art, Articular ; fr, Frontal; jit, Jugal ; la, Laclirymal ; mx, 

 Maxiila ; N, Antorbital vacuity ; na, Nasal ; pa, Parietal ; pmx, Premaxilla ; prd, Predentary ; prf, Prefrontal ; 

 ptf. Postfrontal; qu, Quadrate; quj, Quadrato-jugal ; S, Lateral temporal vacuity; S', Supratemporal vacuity; 

 so, Supraoccipital ; sq, Squamosal (after Cope). 



nostrils, subrectangular orbits, and long and narrow temporal vacuities. Parietal 



ABC 



Fig. 344. 



Trachodon foidki, Leidy. Upper Cretaceous ; 

 New Jersey. Inner (.4), outer (JS), and (C), lateral 

 aspects of mandibular tootli, somewhat worn, 1/1 

 (after Leidy). 



KKi. 34ü. 



Trachodon breviceps, Marsh sp. LTpper Cretaceous ; 

 Montana. A, Inner, and B, Superior aspect of 

 functional and successionäl teeth of dentary, 1/4 

 (after Marsh). 



very small ; premaxillae edentulous. Teeth closely arranged in an alveolar 

 groove opening inwardly, the successionäl teeth forming several tectiform 



