PETERSON: THE AMERICAN DICERATHERES. 



441 



Sacrum. Fig. 28. There are four and often five coossified centra of the 

 sacrum. The two first vertebra? support the ilium, while those in the rear have 

 sharp lateral edges and gradually taper toward the caudals. The neural spine of 



Fig. 27. Diccratherium cooki Peterson. No. 2470a, Coll. Carnegie Museum. 1, lateral view of fifth 

 lumbar; 2, anterior view of same; 3, posterior view of same. X i- 



the first sacral is generally quite slender, but further back the spines are more 

 robust. The sacral foramina are of large size and the coosification between the 



Fig. 28. Diceratherium cooki Peterson. No. 2797, Coll. Carnegie Museum. Lateral and ventral views 



of sacrum. X i- 



