144 EVOLUTION IN THE PAST 



Other pig-like brutes known as Anthracotheres, and first 

 in view in the Eocene, became prominent during Oligocene 

 times. In Europe Hyopotamus was a distinguished genus 

 of this family, and was represented by many forms. The 

 skulls of most of these animals were shaped much like that 

 of an opossum ; but some forms, chiefly North American, 

 had skulls shorter and more pig-like. As anthracotheres had 

 four toes on each foot, and all the toes touched the ground, 

 they doubtless spent the best part of their time in swampy 

 regions. Anatomically they were certainly in a somewhat 

 anomalous condition ; for, to judge by their teeth, they 

 indulged in cud-chewing. Evidently, therefore, they were not 

 turning the Vv'heel of pig-evolution ; nor were they more than 

 in the backwaters of ruminant life. 

 RUMINANTS Primitive ruminants of small size, and deer and gazelle- 

 like in shape, had made their appearance in the Eocene 

 {Xiphodon, Anoplotherium) ; and some of their Oligocene 

 descendants apparently had undergone no modification. 

 Some forms, however, were now timidly chewing their food 

 with teeth of a more decidedly ruminant type (Ccenotheruim). 

 These little creatures — they were not as a rule more than a 

 foot in length — became very numerous in parts of Europe. 

 They were decidedly of chevrotain character ; and some 

 indeed were probably identical in form with living chevro- 

 tains (Prodremotherium, Hycemoschtis). 



Creatures of well advanced chevrotain type were also in 

 some force in North America (Leptomeryx). On that continent 

 also were some allied forms, long-tailed, and of the size of 

 sheep. These were not only primitive in respect to the teeth, 

 but for hoofed animals they were so far old-fashioned as to 

 have their front feet terminating with five toes (Oreodon). 

 There were also a few forms of a more decided archaic 

 character, with the feet clawed instead of hoofed {Agrio- 

 chcerus). 



All the ruminants so far referred to were hornless ; but 

 in North America the males of some allied forms were 

 elaborately armed (Protoceras). The skull was surmounted 

 by a pair of small horns ; and a comparatively large pair 

 adorned the snout ; whilst two good-sized tusks shot down 



