142 



BULLETIN 110, UNITED STATES NATIONAL MUSEUM. 



a 



while, on the other hand, the teeth of Priconodon are much larger than those of the stegosaur. Leidy 

 says, however, that "we observe no necessary relation to the length of animals in proportion with the size 

 of their teeth." 



The dimensions of the centrum are as follows: mm , 



Length 69. 



Depth of anterior face . 49. 



Depth of posterior face > 60. 



Width of anterior face 37. 3 



Width of posterior face 49. 5 



Depth of posterior concavity 9. 5 



Least width of arch facet (ant.) . . : 17. 



Greatest width of arch facet (post) . : 33. 2 



******* ** 



The vertebra is nearest to Stegosaurus, but the equivalent vertebra of Paloeoscincus is unknown, 

 and the association of vertebrae and teeth is in each case conjectural. 



The tapering centrum with flattened articular end, with a surface, although 



badly worn, highly suggestive of sutural roughening, 

 apparently indicates it to belong either to the sacrum 

 or in contact with it. Certainly it does not belong to 

 the mid-dorsal region as determined by Lull. 



Compared with the sacral centra of Ornithomimus 

 sedens, figure 67 suggests it to belong to the vertebra 

 immediately preceding sacral 1 of that specimen, for 

 the reason that sacral 1 has a flattened, rugose, anterior 

 articular end, and from the fact that the present 

 centrum can be readily distinguished from the other 

 centra of this sacral series. Unfortunately, the cen- 

 trum preceding the first sacral in the type of 0. sedens 

 is missing, as it is also in the Ornithomimus skeleton 

 (pi. 35, fig. 2) in the American Museum of Natural 

 History, so that a direct comparison can not be made 

 at this time. 



Compared with the posterior dorsal vertebra of 

 Ornithomimus altus, figured by Lambe (fig. 1, pi. 13, 

 Contrib. to Canadian Paleontology, vol. 3, pt. 2, 1902), such general resemblances 

 were found in the outlines of the centra as to apparently show the correctness of the 

 present provisional assignment of this specimen to the genus Ornithomimus. 



ORNITHOMIMUS MINUTUS Marsh, 1892. 



Ornithomimus minutus Marsh, Amer. Journ. Sci.', ser 3, vol. 43, 1892, p. 452; Sixteenth ann. Rept. 

 U. S. Geol. Survey, 1896, pt. 1,'p. 206.— Hay, Bull. 179, U. S. Geol. Survey, 1901, p. 494.— 

 Nopcsa, F. Baron, Foldtani Kozlony, Budapest, vol. 31, 1901, p. 201. — Osborn, H. F., Contrib. 

 to Canadian Paleontology, vol. 3, pt. 2, p. 12, 1902.— Bowen, C. P., U. S. Geol. Survey, Prof. 

 Paper 90-1, p. 134, 1915. 



Type. — Various portions of metatarsals II, III, and IV now appear to be lost. 

 Type locality. — Denver Basin, Colorado. 

 Horizon. — Denver ,(?), Upper Cretaceous. 

 The oiginal description is as follows: 

 In the same horizon occur the remains of a very minute species, which agrees in all its characters, 

 so far as determined, with the members of this genus. The most characteristic portions secured are the 



b 



Fig. 78.— Vertebral centrum or Orni- 

 thomimus? affinis. No. 8454, U.S.N.H, 

 § nat. size, a, dorsal, 6, lateral views, 

 (After Lull.) 



