PLATE CLXV 



Skull of Brontotheritjm leidyi 



One-third natural size. (See p. 559) 



Referred skull (Carnegie Mus. 93), Hat Creek, Nebr., Cbadron formation, level lower A ("15 or 20 feet from bottom of lower 

 beds" — J. B. Hatcher). This view exhibits the very progressive Brontotherium characters of the dentition in this oldest 

 known member of the phylum, especially the massive swollen canines, the large incisors, the broad submolariform premolars 

 with circular internal cusps, the vestigial external cingula, the blunt internal cingula, and the wide molars, with stout proto- 

 styles and protuberant hypocones. In measurements the dentition nearly equals that in certain specimens of B. halcheri, 

 and the basilar skull length is only 5 centimeters less 



