106 R. 8. Lull — Cretaceous Armored Dinosaur, 



and Stegopelta the armor was continuous over and 

 closely united mth the ilia as well. The limitations of 

 the elements which formed the sacral armor in Nodo- 

 saurus are very indistinct, but in so far as they can be 

 identified are hexagonal. One near the anterior end of 

 the pehds, clearly shown in the photograph (pi. II), and 

 susceptible of measurements, is 13.5 mm. in its greatest 

 (transverse) diameter by about 75 mm. antero-poste- 

 riorly. This plate has a depressed superior surface, 

 whereas that which adjoins its forward outer margin 

 shows a distinct but low nodule (see below). 



Measurements of Pelvis. 



mm. 



Dorsal aspect: 



Length of sacral armor preserved 820 



Breadth of sacral armor preserved 325 



Breadth of sacral armor, est 487 



Breadth of pelvis 1273 



Length of restored right ilium : 



Between perpendiculars 930 



Over curve 1100 



Width of right ilium to notch between diap. I and II . 337 



Length over diapophyses 320 



Breadth of spinous processes 20 



Ventral aspect: 



Length of nine coalesced centra as preserved 730 



Centrum II, width, anterior end 70 



Centrum II, width, center 57.5 



Ant.-post. diameter, diapophysis 43 



Height of vertebra II, about 120 



Height of ilium at pubic peduncle, est 185 



Acetabulum, length . . , 14 



Acetabulum, breadth 17 



Comparison tvith other genera. — A very close resem- 

 blance exists between this pelvis and that of Polacanthus 

 (cf. Hulke 1887, pi. 9), which is of course especially in 

 evidence when the latter is viewed from below. Pola- 

 canthus shows the same characters in the centra, — slender 

 anteriorly with very vague demarcation between the 

 successive vertebrae. Hulke indicates five sacrals, the 

 anterior one bearing light but transversely expanded ribs, 

 as in that which I have called the last sacro-lumbar. He 

 shows in sacrals 2 to 4 bones comparable in their 

 development to the true sacrals of Nodosaurus. His 



