44 THE MAMMALIA. 



sessed 44 teeth, the crowns of which were nearly on the same 

 level. The feet, on the contrary, are very highly specialised and 

 deer-like, there being but two toes. The Miocene genus, Chalico- 

 therium, which occurred in North America, China, India, and 

 Europe, was of an allied family, and comprised species as large as 

 the existing rhinoceros. None of these animals survived the 

 Miocene period. Another family, which was too " mixed up " in 

 type to have a chance of survival, was that of the Oreodo?itidce, of 

 the Miocene and Pliocene of North America. The family is 

 termed by Leidy "ruminating hogs." Their canines were large 

 and pig-like, their pre-molars were of ruminant type, and the 

 molars had the doubly crescentic form of the typical Selenodont 

 Artiodactyls, or true Ruminants. Their feet had four toes, and 

 their number of teeth was complete, in which, of course, they 

 differed both from hogs and sheep. Not content with these con- 

 fused efforts at becoming sheep and hogs at the same time, they 

 developed tear-pits like the typical deer. Exhausted with these 

 incongruous efforts, the Oriodo?itidce disappeared for ever in the 

 Pliocene. 



We have wandered a long way from the true hogs, of which I 

 will only say that though they have persisted in type in a wonder- 

 ful manner, they have as usual decreased both in size and in 

 number of surviving species. The " Erymanthian Wild Boar," 

 found fossil in Attica, was larger than any existing hog, and an 

 immense wild boar existed on the Siwalik Hills of India. The 

 common hog {Sus scrofd) once wandered wild over the greater 

 part of temperate Europe and Asia, and was an early inhabitant 

 of Britain. Its remains are found in the Post-Pliocene forest-bed 

 of Norfolk, but it was completely exterminated as a wild species 

 in that region many centuries ago. 



The majority of living Ruminants are divided into the large 

 families of the Oxen, Sheep, Antelopes, and Deer. The typical 

 Runiinants are highly specialised, both in their limbs and their 

 dentition. There are no incisor teeth in the upper jaw, their 

 place being taken by a callous pad of hardened gum. rhere are 

 also no upper canine teeth, and the only teeth in the upper jaw 

 are six molars on each side. In the front of the lower jaw is a 

 continuous and uninterrupted series of eight teeth ; then there is 



