V. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE LIII 



/H^"#^ 



SKULL FORM IN EOCENE TITANOTHERES 



A, Brachycephalic type, Pdlaeosyops leidyi (Am. Mus. 1516). B, Mesaticephalic type, Manteoceras manteoceras (Am. Mus. 1569). C, Dolichocephalic^ 



type, DolichorliinMi hyognathns (Am. Mus. 1851) 



