126 EVOLUTION IN THE PAST 



service. That reduction at the extremities, however, left 

 them with twice as many functional toes as living pigs 

 possess. Tusks, characteristic of later boars, were not as yet 

 developed ; but the enlarged canine teeth gave promise of 

 these. 



In later Eocene times porcine forms of larger size were 

 wandering about Europe (Choeropotamus). Some of these 

 seem to have had close affinities with monkeys, showing the 

 entanglements of mammal life at this time (Cebo cheer us). 

 The toe question cannot be determined, for these quaint 

 creatures have come down to us minus their feet. 

 BATS At the time when pig-life was coming into view. North 

 American life was also being diversified by small mammals 

 that had acquired the art of flying (Vesperugo). These 

 " wing-handed " creatures can hardly as yet have exhibited 

 much variety of form, and many of them were probably poor 

 flyers. Still, there were forms among them that did not differ 

 much from some of the numerous kinds of bats now hving. 

 Unfortunately no forerunners of these new invaders of the 

 air have been brought to light ; and, so far as geological 

 evidence goes, bats fluttered into the world as suddenly as 

 the flying lizards seem to have done in earlier times. 

 Probably their ancestors had branched off from some insec- 

 tivorous animals, such as were living at the very commence- 

 ment of the Period. The wings, it may well be supposed, had 

 originated as simple folds of skin stretching from limb to 

 limb, resembUng the parachute of the flying squirrel of our 

 own time (Pteromys). 



Well-developed bats were also in Europe in the course of 

 the Period, but they made their appearance later there than 

 on American scenes. 

 PRIMATES Lemur-hke creatures, holding affinities — as did the bats — 

 with primitive insectivores, were visible, it may be re- 

 membered, on the earliest glimpse of Eocene Hfe. They 

 were followed before mid-Eocene times by various forms, 

 mostly of a more definite type (Tomitherium, Microsyops, 

 Hyopodus, etc.). Small, fox-faced, large-eyed creatures were 

 some of these, with well-developed brains indicating mental 

 powers of a comparatively high order {Anaptomorphus). 



