ANALYSIS OP THE DAKOTA GKOUP FLORA. 231 



dentate, a character which is not remarked in any of the Laurineaj of the 

 present epoch. 



But these leaves are very similar to those of the living Sassafra^s offici- 

 nale Nees., showing much the same disposition to remain entire, or merely 

 lobed on one side, as in 8. subinfer/rifoUum, PI. XIV, Fig. 2, of this work, 

 that one can but consider them as original representatives of the genus. 

 Moreoveu, a number of specimens of the same kind were found lioaped 

 together as though derived fnim the same tree, which apparently Ijore 

 some leaves with borders entire, and others having* leaves with the borders 

 mere or less deeply dentate. Then S. mirablle Lesq. (Cret. Fl., PI. xii. 

 Fig. 1) is founded upon trilobate leaves of the same shape as those of S. 

 cretaceum, but more distinctly dentate and so large that they were orignnally 

 referred to Platanus. And this analogy of characters or doul)le affinity- is 

 recognized as well in Platanus recurvata Lesq. (Cret. FL, PI. x, Fig-s. 4, f)), 

 while some of the characters of Cissus or Cissites are seen in the leaves of 

 S. harkerianus Lesq. (loc. cit., PI. xi), and those of Aralia in the species of 

 Sassafras (Araliopsis), a subdivision necessarily adiuitted to indicate the 

 double or multiple characters of a luimber of leaves of the Dakota Group. 

 Even this dualism of generic names is not siifficient to point out and clearly 

 indicate the generic relationship of some of these leaves. Is Sassafras (Arali- 

 opsis) platanoides Lesq. (Cret. and Tert. Fl., PI. vii, Fig. 1) referable to Sas- 

 safras, to Aralia, or to Platanus? The splendid leaf of Sassafras (Araliopsis) 

 dissedum (P\. XIV, Fig. 1, of this volume) has, in the divisions of the lateral 

 lobes, the character of Aralia, while by the size and the general outline it 

 is a Platanus, and still further Ijy the basilar prolongation and the dentate 

 lobes it is merely a variation of Sassafras mirabile. In these leaves the 

 transformation has merely acted upon the division of the lobes, the base, in 

 all the modifications, i-emaining prolonged downward in narrowing and 

 decurring to the petiole. But the metamorphosis further passes to the Iklsc, 

 which becomes rounded peltate and traversed by the ])eti(>le, as in 

 Aspidiophyllum frilohatmn Lesq. (Cret. and Tert. Fl., PL xiii), and takes a 

 new character allying it to that of some leaves of Menisjiermites. Never- 

 theless, Aspidiophyllum leaves are, by their upper trilobate part and entire 

 lobes, so like those of Sassafras that the specimens found deprived of the 

 basilar portion of the leaves have generally been referred to this last genus. 

 And now what is Aspidiophi/lht»i denfafnm (PL XXXIX, Fig. 1, this vol- 

 ume)! It is a distinctly trilobate leaf with bilobate and obtusely dentate 

 lobes like Sassafras dissectum, the base first contracted or strangled and then 



