14 CRETACEOUS AND TERTIARY FLORA. 



first appearance, were considered as more positively related to this family, 

 and which have been described under the generic name of Sassafras. The 

 question of the relation of those leaves which, by their number, seem to 

 be the essential components of the North American Cretaceous Flora, has 

 been already touched upon ("Cret. Fl.," p. 77). But since the publication 

 of that work I have obtained from divers localities a large number of speci- 

 mens of all the forms described there as species, and I have now some 

 more data to offer to the consideration of paleontologists on the subject. 



From historical documents the presence of Sassafras species in the 

 Flora of the Dakota Group is as legitimately presumable as that of species 

 of Laurus or Persea. In his "Flora fossilis arctica," Heer has described as 

 Sassafras arcticum a leaf which, by its form, is similar to those described 

 as Sassafras cretaceum, as remarked by the author, differing merely by its 

 base tapering somewhat less narrowly to the petiole. The nervation is 

 of the same character. Saporta considers the Greenland leaf as a true 

 representative of Sassafras. He has himself published in the "Sezanne 

 Flora," 1 as 8. primigenium, two fragmentary leaves whose base, more nar- 

 rowly tapering, is similar to that of S. Mudgei of the "Cret. Fl.," as well 

 as the lobes which, enlarged in the middle, have that ovate-lanceolate 

 shape so distinctly marked in the present S. officinale. There is also no 

 appreciable difference in the nervation. The lower secondary veins of the 

 middle lobe ascend a little higher in the leaves of the Sezanne Flora, and 

 unite with those of the lateral lobes somewhat nearer the borders of the 

 sinuses. But in some of the specimens of Kansas the same appearance 

 is remarked also, and the difference between the greater or less distance 

 which separates from the sinuses the branches which unite the upper 

 division of the secondary veins is observable upon leaves of S. officinale, 

 this division being sometimes marginal, sometimes curving one to three 

 millimeters lower than the border of the sinuses. Comparing leaves of 

 Sassafras officinale with those represented by Saporta in the "Flora of 

 Sezanne" and the specimens of S. Mudgei from Kansas, it is impossible for 

 me to recognize any character, even any specific difference, by which these 

 leaves could be separated. It is therefore not surprising that Dr. New- 

 berry first, and after him Heer and Schimper, did consider Cretaceous 



•P. 366, tab. viii, figs. 9 and 10. 



