THE EOCENE PERIOD. 303 
peculiarity that they are arranged in a continuous series, with- 
out any gap or interval between the molars and the canines; and 
Fig. 231.—Anoplotherium commune. Eocene Tertiary, France. (After Cuvier.) 
the back teeth, like those of all the Ungulates, are adapted for 
grinding vegetable food, their crowns resembling in form those 
of the true Ruminants. The genera Dichobune and Xiphodon, 
of the Middle and Upper Eocene, are closely related to 
Anoplotherium, but are more slender and deer-like in form. 
No example of the great Ruminant group of the Ungulate 
Quadrupeds has as yet been detected in deposits of Eocene 
age. 
Whilst true Ruminants appear to be unknown, the Eocene 
strata of North America have yielded to the researches of 
Professor Marsh examples of an extraordinary group (L2zv0- 
cerata), which may be considered as in some respects inter- 
mediate between the Ungulates and the Proboscideans. In 
Dinoceras itself (fig. 232) we have a large animal, equal in 
dimensions to the living Elephants, which it further resembles 
in the structure of the massive limbs, except that there are 
only four toes to each foot. The upper jaw was devoid of 
front teeth, but there were two very large canine teeth, in the 
form of tusks directed perpendicularly downwards ; and there 
was also a series of six small molars on each. Each upper 
jaw-bone carried a bony projection, which was probably of the 
nature of a “‘horn-core,” and was originally sheathed in horn. 
Two similar, but smaller, horn-cores are carried on the nasal 
bones ; and two much larger projections, also probably of the 
nature of horn-cores, were carried upon the forehead. We 
may thus infer that Dzwoceras possessed three pairs of horns, 
all of which resembled the horns of the Sheep and Oxen in 
consisting of a central bony ‘‘core,” surrounded by a horny 
