Barbour — Ligamentum Teres in Nebraska Proboscidea. 253 



Fig. 4. 



Fig. 4. a, acetabulum of Mastodon americanus showing a well defined 

 though shallow fossa, b, section through the line xz. c, head of the femur 

 without scar, x 1/10. 



Fig. 5. 



Fig. 5. a, acetabulum of Eleplias imperator showing well-developed fossa one 

 and one fourth inches deep, b, section along the line xz. c, head of femur without 

 scar, x 1/10. 



Fig. 6. 



Fig. 6. a, acetabulum of Eleplias indicus showing obliteration of the ace- 

 tabular fossa. The pectineus pit is on the pubis below x. Compare with 

 figs. 2 and 8. b, section along the line xz. c, head of femur without scar. 

 xl/1. 



