264 KANSAS UNIVERSITY SCIENCE BULLETIN. 



side to side and ends rather broadly, not in a point as does the 

 ulna of Stegosaurus. Viewed from in front the ulna curves 

 strongly outward, especially toward the distal end. It is not 

 so straight as in Stegosaurus. The articular surface for the 

 humerus is small. The radial articulations are, however, well 

 marked, with the upper one forming a distinct fossa below the 

 coronoid process. The lower articular surface of the ulna is 

 well rounded and is oval in outline. The ulna measures 385 

 mm. in total length, 106 mm. antero-posteriorly at the widest 

 part, 45 mm. near the middle of the bone and 60 mm. at the 

 proximal end. 



The radius is represented by fragments only. The head of 

 one of the elements is nearly circular in outline and measures 

 60 mm. in cross section. The articular surface is so abraded 

 that it is impossible to determine its form. 



The ilia (plate LV) are both represented in the collection. 

 The left one is preserved nearly entire. Enough is present to 

 determine the total length and breadth of the bone, and the 

 missing parts have been restored, as is evident from the photo- 

 graph. The portion of the right ilium preserved shows the 

 acetabulum. The description of the ilium will, however, be 

 confined to that of the left side. The bone is elongate and 

 slightly convex upwards ; the convexity becoming strongly 

 pronounced on the outer side. It is 50 mm. thick at the acetab- 

 ulum, but thins to 5 mm. on the inner side and at the anterior 

 end. The thinning is gradual in these two directions. On 

 the outer edge, however, the bone remains thick for over 

 three-fourths of its length, when it gradually thins, but not so 

 much as on the inner edge. The entire dorsal surface of the 

 ilium is covered by a mosaic of thick, bony, scrobiculate plates 

 firmly united to it. These plates are more or less pentagonal 

 in shape and are not all of the same size. On nearly all there 

 occurs, on some in the center, on others near the edge of the 

 plate, a pit, which in life may have supported a more or less 

 elongate horny spine. When the pit is central it is located in 

 the top of the central eminence which occurs on all of the plates. 

 The plates were once, apparently, suturally connected, but 

 there is now no indication of a suture. They form one con- 

 tinuous bony mass over the entire dorsal surface of the ilium. 

 The diameter of the individual plates varies from 56 mm. to 105 



