GEOLOGICAL HISTORY OF THE WALNUTS 229 



and nuts in a late Pliocene lagoon deposit in southern Alabama. 

 In America there are numerous Pleistocene records, the leaves 

 being preserved in the clay deposits of the river terraces and the 

 fruits in the buried swamp deposits. The following still existing 

 species are recorded from the Pleistocene of this country : Hicoria 

 pecan from the old Mississippi bluffs at Columbus, Kentucky: 

 Hicoria alba from a cave in Pennsylvania and from the inter- 

 glacial beds near Toronto, Canada : Hicoria aquatica from North 

 Carolina; Hicoria ovata from Pennsylvania, Maryland and North 

 Carolina: Hicoria villosa from Alabama, and Hicoria glabra from 

 Pennsylvania, Maryland, Virginia and North Carolina. 



The accompanying map (fig. 1) shows the area occupied by 

 the existing species in solid black and the known Tertiary range 

 by vertical lining. It seems probable that the genus spread 

 eastward over Asia but the latter continent has been so little 

 explored that no records are known. 



While the Ice Age exterminated the hickories from Eurasia the 

 genus survived safely in North America and is in no danger 

 of extermination except by the ax of the woodman. Their great 

 tolerance of shade and their ability to respond to the stimulus of 

 increased light combined with their longevity are important factors 

 in their continued existence. While the rodents consume many 

 of the fruits they have probably done so during the whole his- 

 tory of the genus, for nuts gnawed by squirrels are not infrequent 

 in Pleistocene deposits. This is not an unmixed evil for various 

 rodents not only distribute the species but bury the nuts in for- 

 gotten places where they are almost sure to grow. Before the 

 advent of the " civilized ax" many venerable old giant hickories 

 were scattered through our American forests and there are numer- 

 ous records of immense trunks showing 350 or more annual 

 rings. 



THE GENUS JUGLANS 



The name Juglans is a contraction of Jovis glans or nut of 

 Jupiter and the specific name of the species known to the ancient 

 Greeks and Romans is regia, or royal, and is fittingly applied to 

 the magnificent tree which has been so commonly planted through- 



