ii DISTRIBUTION IN THE PAST 83 



period, groups of animals had often a far wider range than 

 at present. To-day the Rhinoceroses are limited to Asia and 

 Africa, and to quite limited parts of the former continent. 

 In the past, these animals were abundant in Europe and 

 North America. Wild Horses now have a range which is not 

 widely different from that of the Rhinoceroses, save that they 

 extend into the more northern regions of Asia. Their remains 

 are abundant both in North and South America. The Hippo- 

 potamus, now confined to Africa, once ranged over Europe, 

 Madagascar, and India. There were plenty of American and 

 European Lemurs. Elephants were nearly world-wide in their 

 range ; and, in short, restricted distribution seems to be on the 

 whole a characteristic of animals of the present day. 



These statements, however, though perfectly true, must not 

 lead to erroneous inferences. It is rather impressed upon the 

 reader, in books which contain sections dealing with geographical 

 distribution, that animals on the whole occupy more restricted 

 areas at present than in the past. There are, however, plenty 

 of examples of groups of extinct creatures which had, so far as 

 we know, quite a restricted range. Thus the Toxodonts were 

 purely South American, as were the Glyptodonts and some other 

 forms. And, on the other hand, the Cervidae of to-day are as 

 widely, if not more widely, distributed than at any other time. 

 The Hares and Rabbits are now nearly universal in range ; the 

 Cats almost so. We meet with Bovidae, even excluding the Sheep 

 and Goats, in all the four quarters of the globe, excluding only 

 South America and, of course, Australia. The Camelidae are still 

 common to both the Old and the New Worlds. 



During certain periods of the Tertiary epoch it is true that 

 there was more similarity between Europe and North America 

 than there is at present. It would have been quite necessary to 

 unite both into a Holarctic area, such as is now insisted upon by 

 many ; but the reasons for this union would then have been 

 stronger. The fact is, however, that the closer resemblances were 

 due to the larger number of families of animals which existed 

 then than now ; these have decayed away from both continents, 

 and allowed the unlikenesses between the mammalian fauna of 

 both to become evident. But the likenesses which still sur- 

 vive have led many to associate the two regions closely together. 



So far as the history of a genus or family or larger division 



