346 Marsh — Restorations of Claosaurus and Ceratosaiirus. 



that they were covered with hoofs, and not with claws. The 

 limb as a whole was thus adapted to locomotion or support, 

 and not at all for prehension, although this might have been 

 expected from its small size and position. 



The elongation of the fore arm and maims is a peculiar 

 feature, especially when taken in connection with the ungulate 

 phalanges. It may, perhaps, be explained by supposing that 

 the animal gradually assumed a more erect position until it 

 became essentially a biped, while the fore limbs retained in a 

 measure their primitive function, and did not become prehen- 

 sile, which was the case in some allied forms. 



The pelvis has already been described by the writer. Its 

 most notable features are seen in the pubis and ischium, the 

 former having a very large expanded prepubis with the 

 postpubis rudimentary, while the shaft of the ischium is 

 greatly elongated. 



The femur is long, and the shaft nearly straight. The great 

 trochanter is well developed, while the third trochanter is large 

 and near the middle of the shaft. The external condyle of 

 the distal end is projected well backward, indicating great 

 freedom of motion at the knee. 



The tibia is shorter than the femur, and has a prominent 

 cnemial crest. The distal end is much flattened, and the 

 astragalus is closely adapted to it. The fibula is very straight, 

 with its lower end flattened and closely applied to the front 

 of the tibia. The calcaneum is large, with its concave upper 

 surface closely fitted to the end of the fibula. Of the second 

 row of tarsals, only a single one appears to be ossified, and 

 that is very small and thin, and placed between the calcaneum 

 and the fourth metatarsal, nearly or quite out of sight. 



The hind foot, or pes, had but three digits, the second, third, 

 and fourth, all well developed and massive. The terminal 

 phalanges were covered with broad hoofs. The first and fifth 

 digits were entirely wanting. 



All the limb bones in Claosaurus are solid, thus distinguish- 

 ing it from Hadrosaurus. The separate ischium, not coossified 

 with the pubis, the absence of a fourth digit in the hind foot, 

 and other marked characters, also make the genus distinct 

 from Pteropelyx, the skull of which is not known. 



The reptile here restored was nearly thirty feet in length 

 when alive, and about fifteen in height in the position repre- 

 sented in Plate YI. The remains were obtained by Mr. J. B. 

 Hatcher and Mr. A. L. Sullins, in the Ceratops beds of the 

 Laramie, in Wyoming. Among the associated fossils are the 

 gigantic Trieeratops and Torosaurus, which were also herbiv- 

 orous Dinosaurs, and with them were found the diminutive 

 Cretaceous mammals recently described by the writer. 



