U. S. GEOLOGICAL SURVEY MONOGRAPH 55 PLATE CXHV 



SKULLS OF MEGACEROPS COPEI AND M. BUCCO 



One-fourth natural size. (See pp. 543, 544, 548, also Pis. CXLIO and CXLV.) A, Mega- 

 cerops copei, skull V', type (Nat. Mus. 4711), Indian Draw, Big Badlands, S. Dak., 

 Chadron foi-mation, level upper C (Hatcher). In this front view lateral crushing 

 has emphasized the eredt position of the horns. The close appression of the zygO' 

 mata to the brain case is also due to crushing. This skull differs from M. acer, espe-- 

 cially in the horns. Figure prepared under the dirc(5lion of Professor Marsh. B, 

 Female skull referred to 'Megacerops bucco, skull O^ (Nat. Mus. 4705), South Dakota, 

 Titanotherium zone, upper levels of middle part (Hatcher). Figure prepared under 

 the diretftion of the author. Vertical crushing has diminished the vertical and increased 

 the transverse diameters of this specimen. Its resemblances to the male of M. hucco 

 as well as to the female of M. acer may be noted in Plates CLV and CL, B 



