O. C. Marsh — Restoration of Brontops robustus. 165 



The pelvis is very wide, and transversely expanded, as in the 

 elephant. The femur is long, and has the third trochantei 

 rudimentary. The tibia and fibula are quite short. The cal- 

 caneus is very long, and the astragalus is grooved above. 

 There are only three digits in the pes, the first and fifth having 

 entirely disappeared. 



• Diplacodon of the Upper Eocene is clearly an immediate an- 

 cestor of the Brontotheridm, while Paloeosyops and Bimnohyus 

 of the Middle Eocene are on the more remote ancestral line. 

 The nearest related European form is the Miocene Ghalico- 

 therium. No descendents of the Brontotheridce are known. 



Menodus, Megacerops, Brontotherium, Symborodon, Menops, 

 Titanops, and Allops, all belong to the family Bro?itotheridm, 

 and their relation to the . genus here described, and to each 

 other, will be fully discussed in the monograph, to which 

 reference has already been made. 



