1 74. 0. C. Marsh — The gigantic Ceratopsidce, 



individual, proving that the animal walked on all four feet. 

 The radius and ulna are comparatively short and stout, and the 

 latter has a very large olecranon process. 



There were rive well-developed digits in the manus. The 

 metacarpals are short and stout, with rugose extremities. The 

 distal phalanges are broad and hoof-like, showing that the fore 

 feet were, distinctly ungulate (Plate IX, figures 1-6). 



The Pelvis. 



The pelvis in this group is very characteristic, and the three 

 bones, ilium, ischium, and pubis, all take a prominent part in 

 forming the acetabulum The relative size and position of 

 these are shown in the diagram (Plate VII, figure 1), which 

 represents the pelvic elements as nearly in the same plane as 

 their form will allow, while retaining essentially their rela- 

 tive position in life. 



The ilium is much elongated, and differs widely from that in 

 any of the known groups of the Dinosauria. The portion in 

 front of the acetabulum forms a broad, horizontal plate, which 

 is continued backward over the acetabulum, and narrowed in 

 the elongated, posterior extension. Seen from above, the ilium, 

 as a whole, appears as a nearly horizontal, sigmoid plate. From 

 the outside, as shown in the diagram, the edge of this broad 

 plate is seen. 



The protuberance for the support of the pubis is com- 

 paratively small, and elongated. The face for the ischium is 

 much larger, and but little produced. The acetabular face of 

 the ilium is quite narrow. 



The pubis is massive, much compressed transversely, with 

 its distal end widely expanded, as shown in the figure (Plate 

 VII). There is no post-pubis. The pubis itself projects for- 

 ward, outward, and downward. Its union with the ilium is 

 not a strong one. and is similar to that seen in the pubis of 

 Stegosaurus. 



the ischium is smaller than the pubis, but more elongate. 

 Its shaft is much curved downward and inward, and in this 

 respect, it resembles somewhat the corresponding part of the 

 pubis of the ostrich. There is no indication that the two 

 ischia met closely at their distal ends, and they were probably 

 united only by cartilage. 



A comparison of this pelvis with that of Stegosaurus shows 

 some points of resemblance, but a wide difference in each of 

 the elements. The pubis corresponds, in its essential features, 

 to the pre-pubis of Stegosaurus, but the post-pubis is wanting.* 



* One pubis recently discovered, and represented in Plate VII, has a short, 

 splint-like process, which may, perhaps, be a remnant of a post-pubic element, 

 although it does not have the position of the post-pubic bone in other Dinosaurs. 



