Peterson: The Osteology of Promerycochoerus. 



189 



anterior portion, but otherwise the pelvis has the usual antero-pos- 

 terior elongation and the deep, narrow pelvic cavity, characteristic 

 of the family. The point of the ilium is rather heavy and rugose, 

 affording extensive surfaces for muscu- 

 lar attachments. From this rugosity 

 backwards to the iliosacral contact is 

 a very prominent ridge on the internal 

 face of the ilium, which also serves for 

 the attachment of muscles. The 

 spines of the sacrum when in position, 

 rise above the superior iliac border. 

 The latter is rounded from before 

 backward and the ilium is rapidly con- 

 tracted to a notch back of the sacro- 

 iliac contact much as in Merycoidodon 

 culhertsoni, Mesoreodon, and other 

 genera of the family. The acetabular 

 border of the ilium forms a long and 

 gently concave sweep from the point 

 of the ilium to the anterior border of 

 the acetabulum. The latter is rather 

 small, though deep, and the pit for 

 the ligamentum teres is unusually 

 deep. The cotyloid notch is deep, 

 but narrow, and relatively smaller 

 than in Merycoidodon, and much 

 smaller than in Mesoreodon chelonyx. 

 The ischium is elongated and robust, 

 with a broad rough surface over the 

 acetabulum which terminates above 

 in a deep ridge or spine. This spine 

 again decreases in prominence to 

 form the lesser sacro-sciatic notch 

 after which the ischium again sud- 

 denly rises in an upward and outward 

 direction to form the high and robust ischial tuberosity. The broad 

 surface of the posterior portion of the ischium is sub-triangular in out- 

 line, very high, terminating above in the large tuberosity mentioned 

 and below in a heavy and rugose area, which is developed into a large 

 tubercle on the posterior ventral angle of the symphysis. The ascend- 



FiG. 29. Lateral view of sacrum 

 and pelvis of Promerycochcerus carri- 

 keri. No. 1081. ^ nat. size. 



