694 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



other parts of the skeleton; a well-preserved pelvis 

 referred by Marsh to B. gigas and figured in Plate 

 CCXXXI (Nat. Mus., no number) ; and a pelvis in the 

 National Museum (No. 4262) probably associated with 

 skull and limbs referred to B. gigas. 



The pelvis of B. gigas differs from that of Brontops 

 robustus in its greater relative width and in having 

 the outer iliac crest produced more downward and 

 less directly outward. 



Femur. — The femur of B. leidyi (Carnegie Mus. 93) 

 lacks the proximal end, but the bone appears to be 

 relatively broader than in Brontops rohustus (type). 

 The characters of the bone in B. gigas are not known. 



Tihia. — The tibia of B. leidyi (Carnegie Mus. 93) is 

 relatively wider at the proximal end than that of B. 

 roiustus. 



Pes. — The pes of Brontotherium is supposed to be 

 represented by three metatarsals (PI. CCXXXII) and 



FiGUKE 631. — Manus and pes referred to Brontotherium gigas hatcheri 

 Nat. Mus. 4262. One-fourth natural size. 



Measurements of pelvis in Brontotherium gigas and Brontops 

 robustus, in millimeters 



some phalanges (PI. CCXXXV), which Marsh referred 

 to B. gigas; by an incomplete pes (Am. Mus. 1047); 

 and by a partial pes which may be associated with the 

 skeleton of B. gigas (Nat. Mus. 4262). The pes, as a 

 whole, is extremely short and wide, the third meta- 

 tarsal measuring 160 millimeters in length and 76 in 

 maximum width near the distal end, as compared with 

 225 in length and 88 in width in B. rohustus (type). 

 The index of the third metatarsal is thus 47 in B. 

 gigas and 40 in B. roiustus 



