U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE CLXXXV 



SKULLS OF BRONTOTHERIUM CURTUM 



One-fifth natural size. (See p. 575^ also Pis. CLXXVH and CLXXXIII.) A, Occiput referred to Brontotherium curtum (Am. 

 Mus. 6346), Horsetail Creek, northea^em Colorado, Chadron: ormation. As remarked above (PI. CLXXXIII), this 

 specimen is one of the cotyp^s seledled by Cope for his species of "Symhorodon bucco." The insertion areas for the liga- 

 mentum nuchae and for the re(5tus capitis lateralis muscles are well shown. The skull is a little crushed downw/ard. 

 B, Front view of skull referred to Brontotherium curtum? (Nat. Mus. 4946), skull q. Big Badlands, S. Dak. (TIndian Drawr), 

 Chadron formation, level upper C (Hatcher). This view shows well the elevation of the nasal region in uncrushed 

 skulls. The right horn has been broken off during life. The infraorbital canals are subcircular, as in other brontotheres 



