OSTEOLOGY OF THE ARMORED DINOSAURIA. 



51 



sacrum the neural processes are of about equal dimensions. The summits of all 

 are moderately expanded transversely. 



A deep cupped capitular facet is present on all of the vertebrae posteiior to the 

 fifteenth, and its position on the side of the arch at the base of the transverse process 

 remains practically unchanged, except on two or more of the posterior dorsals, 

 where it is produced outward on a thick buttress of bone (fig. 20, 1), but to a less 

 degree than in the posterior dorsals of either Camptosaurus or Triceratops, where it 

 is found more on the anterior border of the transverse process. 



Z-: 



FIG. 20. — POSTEEIOE DOKSAL VEETEBEA OF STEGOSAURUS SP. CAT. NO. 6531, U.S.N.M. } NAT. 



size. 1, Fbontview. 2, Side view, d, Diapophysis; n, neural canal; p, paeapophtsis; 

 s, neural spine; z, anteeioe zygapophysis; z', posteeiok zygapophysis. 



The transverse processes are comparatively stout, subtriangular in cross-section, 

 and are rather unique in their great upward inclination from the horizontal, which 

 in the anterior and mid-dorsal region rise to nearly the height of the neural spine. 

 This inclination of the transverse processes of the anterior and mid-dorsal regions 

 is nearly 50° above the horizontal, but as we approach the sacrum they become 

 somewhat more depressed. 



The elevation of these processes is considered by Lull * " a wonderful adaptation 

 for bearing the great dermal plates with which the back is adorned." 



' Amer. Journ. Sci., vol. 30, 1910, p. 367. 



