54 



THE CERATOPSIA. 



The median caudals, as shown in fig. 58, have slightly biconcave and short centra. The 

 vertical and transverse diameters are nearly equal. The transverse processes are shorter and 

 less elevated, and the neural arches are proportionally somewhat higher than in the first caudal. 



Tig. 55.— Superior view of sacrum, with ilia in position, of Triceratops prorsus, No. 4842, U. S. National Museum, in mounted skeleton. 



a, Anterior; p, posterior; il, ilium. 



