246 TREE ANCESTORS 



disrupted Austro-Hungarian empire (Styria, Carinthia, and Croa- 

 tia). One of the gums found in the latter region is also recorded 

 from Siberia. 



The Miocene witnessed the last known gums in Europe, their 

 extinction on that continent having apparently been due to cli- 

 matic changes long anterior to the glacial period for none are known 

 from European Pleistocene deposits which is a reasonable guerdon 

 of their absence at that time for many of these Pliocene plant beds 

 were swamp deposits. The known Pliocene or late Tertiary gums, 

 3 in number, are all North American, and very much like some of 

 our existing American species, of which they were undoubtedly 

 the ancestors. They come from New Jersey and southern Alabama. 

 The Pleistocene gums are likewise North American and represent 

 still existing species. They are known from New Jersey, Maryland, 

 Virginia, North CaroHna, Alabama, and Kentucky. 



