OLIGOCENE PERIOD I43 



doubtless exercised a wise discretion in living in strict retire- 

 ment. 



At the close of the Eocene, ancestral horses had had their horses 



teeth more strongly crowned, enabling them to masticate 



a more varied vegetation. They had also increased from 



the size of fox-terriers to that of foxes ; and their feet, 



although continuing four-toed and three-toed, were more 



compact than those of the earlier forms. The record of the 



race in Europe in Oligocene times is unfortunately very 



imperfect. It is clear, however, that the teeth of the animals, 



although stiU short-crowned, were stouter and stronger than 



those of earlier forms {Anchilophus). From North America 



fuller evidence of progress has been obtained. Here, too, 



the Httle creatures were becoming more strongly toothed 



(Mesohippus). They were also larger-headed and taller, 



attaining in some cases the height of good-sized harriers. 



They also exhibited progress in a greater compactness of 



the feet, as they were three-toed on the fore as well as on 



the hind limbs. The side-toes, no doubt, touched the ground 



when the animal was grazing, but they were probably little 



more than passengers in the gallop. 



Pig-life was progressing, for some forms as large as wild swine 

 boars (Hyotherium, etc.), and much bigger, therefore, than 

 the hare-sized creatures of Eocene times, were now grubbing 

 about in the forests. All the animals seem to have had four 

 usable toes on each foot, as with the earlier forms ; but the 

 canine teeth, although not of tusky status, were now well 

 developed. The creatures were of a composite character, 

 some of them partly pig, and partly— though to a less degree- 

 peccary. In some North American forms the pig and peccary 

 characteristics were in reverse proportion (Perchcerus). 



There were also various other pig-like creatures ; but 

 they were, so to speak, merely players of incidental music 

 to the main theme. Some fine-looking brutes were among 

 them, as large as rhinoceroses (Elotherium). These probably 

 had long given up frequenting boggy lands, for their feet were 

 more compact than those of modem pigs. Indeed the side- 

 toes, which would have been of service for resistance in 

 swamps, had aU but disappeared. 



