chap, va.] MAMMALIA OF THE NEW WORLD. 139 



and Upper Eocene, no remains of this order have been found ; 

 and in 1869, Dr. Leidy remarked on the small average size of 

 the extinct North American mammalia, which were almost all 

 smaller than their living analogues. Since then, however, won- 

 derful discoveries have been made in deposits of Middle Eocene 

 age in Wyoming and Colorado, of a group of huge animals not 

 only rivalling the elephants in size, but of so remarkable and 

 peculiar a structure as to require the formation of a new order of 

 mammals — Dinocerata — for their reception. 



This order consists of animals with generalised Ungulate and 

 Proboscidean affinities. The lower jaw resembles that of the 

 hippopotamus ; they had five toes on the anterior feet and four on 

 the posterior ; three pairs of horns, the first pair on the top of the 

 head, large and perhaps palmated, the second pair above the eyes, 

 while the third and smallest stood out sideways on the snout. 

 They had enormous upper canines, of which the roots entered 

 the middle horn cores, no upper incisors, and small molars. 

 Professor Marsh believes that they had no trunk. The remains 

 discovered indicate four genera, Dinoceras (3 sp.), Tinoceras 

 (2 sp.), Uintatherium (1 sp.), and Eobasileus (2 sp.). Many other 

 names have been given to fragments of these animals, and even 

 those here given may not be all distinct. 



Another new order, Tillodontia, recently established by Pro- 

 fessor Marsh, is perhaps yet more remarkable in a zoological 

 point of view, since it combines the characters of Carnivora, 

 Ungulata, and Rodents. These animals have been formed into 

 two families, Tillotheridse and Stylinodontidse; and three genera, 

 Tillotherium, Anchippodus, and StylinodontAa. All are from the 

 Eocene of Wyoming and New Jersey. Perhaps to these must be 

 added Elotherium from the Miocene of Dakota, the other forms 

 being all Eocene. They were mostly animals of small size, 

 between that of the capybara and tapir. The skull resembled in 

 form that of a bear ; the molar teeth were of Ungulate type, and 

 the incisors like those of a Rodent ; but the skeleton was more 

 that of the Ursida?, the feet being plantigrade. Professor Cope 

 has since described three new genera from the Eocene of 

 New Mexico, Ectoganus, Calamodon, and Esthonyx, comprising 



