372 PALAEONTOLOGY AND EVOLUTION xi 



dry land ; and if the condition of its eastern and 

 western ends offered as wide contrasts as the 

 valleys of the Ganges and Arabia do now, many 

 forms which made their way into Africa must 

 have been different from those which reached 

 the Dekhan, while others might pass into both 

 these sub-provinces. 



That there was a continuity of dry land between 

 Europe and North America during the Miocene 

 epoch, appears to me to be a necessary consequence 

 of the fact that many genera of terrestrial 

 mammals, such as Castor, Hystrix, JElephas, 

 Mastodon, Egiius, Hipparion, AnchitJierium, Rhino- 

 ceros, Cermis, Amphicyon, Hycenarctos, and Mackair- 

 odus, are common to the Miocene formations of 

 the two areas, and have as yet been found (except 

 perhaps Ancliitherium) in no deposit of earlier age. 

 Whether this connection took place by the east, 

 or by the west, or by both sides of the Old 

 World, there is at present no certain evidence, and 

 the question is immaterial to the present argu- 

 ment ; but, as there are good grounds for the 

 belief that the Australian province and the Indian 

 and South-African sub-provinces were separated 

 by sea from the rest of Arctogaea before the 

 Miocene epoch, so it has been rendered no less 

 probable, by the investigations of Mr. Carrick 

 Moore and Professor Duncan, that Austro-Columbia 

 was separated by sea from North America during 

 a large part of the Miocene epoch. 



