110 R. S. Lull — Cretaceous Armored Dinosaur, 



situated somewhat higher on the centrum than in No. 4 

 and apparently the processes themselves were lighter. 

 The same shallow vertical groove is discernible on the 

 centra, and the surface of the latter is slightly rugose 

 toward the articular faces, especially ventrally. A 

 slight fore-and-aft ridge runs from the hinder margin 

 forward about two thirds the length of the bone above 

 the diapophysis. 



Caudals 16 and 17 (fig. 3). — These vertebrae were also 

 in contact, and No. 16 particularly is very well preserved. 

 It also has numerous small dermal ossicles associated 

 with it, together with an oval armor plate (see below). 



Fig. 6. — Left tibia and fibula of Nodosaurus textUis. A, anterior, B, pos- 

 terior, C, external aspect, a, coalesced astragalus; c, calcaneum; /, fibula; 

 t, tibia. One-eighth natural size. 



Caudal 16 is relatively longer and slenderer of centrum 

 than are caudals 4 to 10, implying a gap of perhaps five 

 vertebrae between it and the tenth. The articular faces of 

 the centrum are essentially plane and the centrum itself 

 begins to exhibit the distinct longitudinal ridges seen 

 in Nos. 23 and 24. Diapophyses are still present and arise 

 about the middle of the bone. The spinous process is 

 strong and prolonged fore and aft, the postzygapophyses 

 merging into the posterior angle of the spine. Hori- 

 zontal laminae are faint, but distinct. Both zygapophyses 

 overhang the centrum. 



Caudals 23 and 24 {^g, 3). — These are again in contact, 

 with an estimated omission of perhaps six vertebrae 

 between them and No. 17. Here the diapophyses are 



