206 DINOSAURS OF NORTH AMERICA. 



apparently pneumatic. The .sacrum measures 15 inches iu length, and 

 the twelve caudals following occupy a space of 31 inches. The known 

 remains indicate a reptde about 8 or 10 feet in length. A terminal 

 phalanx ot the fore foot is represented on page 20.5. 



In the same horizon occur the remains of a very minute species, 

 which agrees in all its characters, so far as determined, with the mem- 

 bers of this genus. The most characteristic portions secured are the 

 metatarsal bones, and these show the same features exhibited in the 

 type species of the genus, 0. velox. They are, however, so much 

 smaller as to suggest that they may pertain to a bird. Various por- 

 tions of the second, third, and fourth, metatarsals are known, and the 

 distinctive feature is seen in the third, which has the upper part of the 

 shaft so attenuated that it may not reach to the tarsus. The second 

 and fourth metatarsals are very long and slender. This unique animal 

 was about the size of the common fowl. The species has been called 

 Orn ithomim us m i mititx. 



The large species described by the writer as Ornithomimus c/randis 

 belongs in essentially the same horizon. Portions of two other skele- 

 tons have since been obtained, which apparently pertain to this species. 

 In one of these the femur, tibia, and fibula are in good preservation, 

 and they clearly demonstrate that this reptile was one of the largest of 

 the Theropoila. The femur and tibia have each a very large cavity in 

 the shaft, with well defined walls. Even the fibula has a cavity iu its 

 upper portion. Iu the other specimen the second metatarsal is in fair 

 preservation and shows the same form as in the type of the genus. 



There is much probability that this gigantic carnivore was one of 

 the most destructive enemies of the herbivorous Ceratopsidte, next to 

 be described. 



PREDENTATA. 

 CERA TOPSIDE. 



The huge horned dinosaurs, from the Cretaceous, recently described 

 by the writer, 1 have now been investigated very carefully, and much 

 additional light has been thrown upon their structure and affinities. 

 A large amount of new material has been secured, including several 

 skulls, nearly complete, as well as various portions of the skeleton. 



CERATOPS BEDS. 



The geological deposits, also, in which their remains are found have 

 been carefully explored during the last few years, and the known locali- 

 ties of importance examined by the writer, to ascertain what other 

 fossils occur in them and what were the special conditions which pre- 

 served so many relics of this unique fauna. The definite horizon in 

 which these strange reptiles occur has been called by the writer the 

 Ceratops beds, from the type genus Ceratops, and its position is shown 

 in the section on page 145. 



'American Journal of Science, 1888-1894. 



