EXPLANATION OF PLATE 8. 



Omphalosaurus nevadanus, n. gen. and sp. Superior aspect of a portion of 

 the mandible with several displaced head bones and two vertebrae. A, 

 angular; Sa, supra-angular; D, dentary; Ft, pterygoid; V, vertebrae; 

 a, 1), and c, doubtful elements. Middle Triassic, South Fork of Amer- 

 ican Canon, West Humboldt Eange, Nevada. X %. 



