868 SYSTEMATIC PALEONTOLOGY 



novsky identifies somewhat doubtful remains from the Cenomanian of 

 Bohemia as this species. Probable Sassafras fruit has been found in the 

 same strata with S. acutilolum, 1 tending to show that it is a true Sassafras, 

 notwithstanding its dissimilarities; however, this is not certain, as the 

 leaves and fruits were not found associated. 



There is considerable doubt as to whether or not these Coastal Plain 

 leaves are generically related to Sassafras. Whether the Dakota group 

 forms are those of Sassafras it is not easy to decide. No modern Sassafras 

 leaves have the primaries and the lateral lobes so nearly horizontal; the 

 secondaries are not so uniformly regular, nor do they curve upward to 

 join the next above at a point. In the modern leaf an outwardly and 

 downwardly directed branch from the latter is emphasized. There is 

 never such an open sinus, amounting as it does to nearly 90, and the lobes 

 in the modern leaf have their margins inflated and not straight. In these 

 ancient leaves the sinus seldom has a marginal vein, the secondary in this 

 region usually forking and striding it, or curving to join its neighbor. 

 The secondary system seems to be uniform throughout the leaf, while in 

 the modern leaf there is always evidence of changed conditions in that 

 region around the sinus; the secondaries or their representatives from 

 both the primaries and the midrib are changed in size and direction, and 

 usually belong to the tertiary system. None of the Dakota leaves of this 

 species show the characteristic basal venation of the modern leaf. While 

 we should not, necessarily, expect Cretaceous species to conform to the 

 modern type, still the character of the secondary system in the former is 

 so different from what would obtain in a leaf descended from a simple 

 ancestor, such as Sassafras is thought to have done, that we are inclined 

 to associate these leaves with those trilobed forms which have been referred 

 to Aralia or Sterculia, laying aside, for the present, any consideration as 

 to whether or not they are true species of Aralia and Sterculia. 



However, in view of the present uncertainty, and because of the havoc 

 to the stratigraphic value of these leaves which would be wrought by any 

 change of name, they are retained in the genus Sassafras pending more 

 positive evidence of their affinity. 



1 Lesquereux, Mon. U. S. Geol. Survey, vol. xvii, p. 230, 1892. 



