Prof. 0. C. Marsh — Gigantic Ceratopsidce. 245 



The protuberance for the support of the pubis is comparatively 

 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 (5). There is 

 no post-pubis. The pubis itself projects forward, outward, and 

 downward. Its union with the ilium is not a strong one, and is 

 similar to that seen in the pubis of Stegosauriis. 



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.' 



The Posterior Limbs. — The femur (Woodcut, Fig. 8) is short, 

 with the great trochanter (t.) well developed. The shaft is com- 

 paratively slender, and the distal end much expanded. The third 

 trochanter is wanting, or represented only by a rugosity. 



The tibia (Woodcut, Fig. 9) is of moderate length, and resembles 

 that of Stegosaurus. The shaft is slender, but the ends are much 

 expanded. The fibula is very slender, and the distal end was 

 closely applied to the front of the tibia (Woodcut, Figs. 9 and 10/.). 

 In adult individuals, the astragalus is firmly coossified with the 

 distal end of the tibia, as in Stegosaurus (Figs. 9 and 10 a, a). 



The metatarsal bones which were functional are rather long, but 

 massive (Woodcut, Figs. 17-19). Their phalanges are stout, and 

 the distal ones broad and rugose, indicating that the digits were 

 terminated by very strong hoofs (Woodcut, Figs. 20, 21, 22). 



All the limb bones and vertebrae in Triceratops, and the nearly 

 allied genera, are solid. 



Fig. 11. — Metacarpal of THceratops prorsus, Marsli (front view), one-eig]itli 

 natural size. Figs. 12 and 13. — The same bone ; side and back views. 



The Dermal Armour. — Beside the armature of the skull, the 

 body also in the Ceratopsidce was protected. The nature and 

 position of the defensive parts in the different forms cannot yet be 



^ The pubis recently discovered, and represented in "Woodcuts Figs. 5, 6, 7, has a 

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

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



