No. 4S7] 



PLKISTOCEXE FLORA OF r'.l.V.lD.l 



445 



Norway maple will show that although thev difier materially with 

 respect to venation, they resemble one another in a verv remark- 

 able manner as to tiie form of the sinuses and the detailed con- 

 figuration of the lobes. These resemblances between two such 

 well defined species, are precisely of the same order as those which 

 are recognized in a comparison of the fossil with the sugar maple. 

 It therefore becomes obvious that in the absence of flowers and 

 fruit, it is not possible to effect a satisfactory specific differentiation 



Fig. 1. Acer pleistocenicum Pewh. X 0.55. 



on the basis of leaf form only, but upon this basis the form now 

 under discussion must be regarded as altogether different from 

 any previously recognized fossil or recent species. The diagnosis 

 of this leaf may be stated as follows : — 



Leaves strongly and palmately veined ; two principal veins aris- 

 ing at the base of the midrib and traversing the principal lobes; 

 two inferior veins of varying prominence arising from near the 

 same position but extending diagonally downward into the inferior 

 lobes. Leaves three to five lobed; the two liasal lobes variable, 



