The Romance of a Wayside Weed. 59 



and the wolf have become extinct within the historical 

 period ; and the wild white cattle even now survive 

 sparingly in Chillingham Park and a few other 

 scattered places. Clearly, as none of these animals 

 or their ancestors can have been in Britain 8o,oco 

 years ago, they must have come into Britain at some 

 later date, across a wide bridge of solid land. For 

 Mr. Wallace has conclusively shown that islands 

 which have never formed part of a mainland never 

 have any terrestrial mammals at all ; and that a very 

 narrow strait is quite sufficient to prevent the passage 

 of mammals from one island to another. The sound 

 which divides the Indo-Mala\-an region from the 

 Australian region is hardly wider than that which 

 separates England from France ; yet not one single 

 Australian mammal has ever reached the Indo- 

 Malaj'an region, and not one single Indian mammal 

 has ever reached Australia. The kangaroos, wombats, 

 phalangers, and cassowaries of the one district are 

 ■ quite distinct in type from the elephants, tapirs, tigers, 

 deer, and monkeys of the other. So that our numer- 

 ous existing English fauna must certainl)- have crossed 

 over on dry land. 



We may take it for granted, then, that the mass of 

 British plants came in, from the east and south-east, 

 immediately after the ice of the glacial epoch had 



