EOCENE PERIOD 139 



The Eocene world no doubt contained a great deal of 

 vaguely developed and highly composite life ; but it pos- 

 sessed a marine population — ^vertebrate and invertebrate — 

 not greatly differing from that of our own times. Quaint 

 reptile forms — ^land-dwellers, sea-rovers, and voyagers in the 

 air — had become extinct ; and reptiles of all existing Orders 

 and Sub-orders were on the scene. Various birds, comparable 

 with living forms, were appearing ; and divers mammals 

 abounded, awaiting indeed differentiation in many cases, 

 but more or less representative of all existing Orders. Trees 

 also and shrubs intimately related to growths of our own 

 time were spreading far and wide. Modern life had dawned. 



