U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE L 



TYPE SKULLS OF PALAEOSYOPS LEIDYI AND MESATIRHINUS PETERSONI 



A, Palaeosyops leidyi, type (Am. Mus. 1544), Bridger Basin, Wyo., level Bridger C or D 

 skull (Am. Mus. 12184), CattaU Springs, Bridger Basin, Wyo., level Bridger D 3; lov 

 Meadows. Washakie Basin, Wyo., level Washakie A. Both one-third natural size 



Mesatirhinus petersoni, type 

 aw (Am. Mus. 1512), Laclede 



