PETERSON: THE AMERICAN DICERATHERES. 



447 



The acetabulum is well rounded and deep; the pit for the round ligament is quite 

 deep and the cotyloid notch broad. The obturator foramen is very large and 

 ovate in outline. The sciatic notch of the ischium is well-defined by the sudden 

 termination of the spine and the heavy and suddenly upward, or outward, turned 

 tuber ischii. The prominence of the latter tuberosity is subject to some variation 



Fig. 35. Fig. 36. 



Fig. 35. Diceralherium cooki Peterson. No. 2460, Coll. Carnegie Museum. Posterior and anterior 



views of femur. X i. 

 Fig. 36. Diceratherium cooki Peterson. No. 1840, Coll. Carnegie Museum, 1, anterior view of tibia 



and fibula; 2, posterior view of same. X 3. 



in different individuals. In fact there is in this species a considerable degree of 

 variation in the robustness of the pelvis in the large collection before us. This, 

 in my judgment, is due to age and sex. 



The femur is quite long. The shaft, when seen from the front, is quite straight, 

 but on a rear view appears curved, due to the prominence of the different trochanters 

 (See Fig. 35.) The third trochanter, though large, is not the long, forward, and 



