INTRODUCTION. 17 



their size, all are of the same character as in S. mirabile. But in the pel- 

 tate base of the leaves there is another character which, separately con- 

 sidered, relates the leaves to the Menispermacece. We thus have Sassafras 

 already represented in those leaves by S. Mudgei, and less positively by 

 S. acufilobum; Araliopsis, to which are referable S. mirabile, with the den- 

 tate S. crefaceum, S. ohtusum, S. dissectum, S. platanoides, Platanus recurvata, 

 and in a new generic division, under the name of Aspidiophjllum, the 

 leaves which, either Aralia or Sassafras, by their upper trilobate part, 

 are necessarily separated from these genera by their auricled peltate 

 appendage. Still, the subdivisions in the classification of the peculiar and 

 so-called Sassafras leaves have to be pursued further, for by degi'ees and 

 by the gradual obliteration of their lobes they become round or truncate, 

 or broadly pointed at the top, preserving more or less the narrowed base, 

 tapering to a long petiole, and the trifid craspedodrome nervation from a 

 •distance above the borders, and thus they become more evidently related 

 to other vegetable orders. One species is a true Hedera, another passes 

 to the Hamamelideo}, and a number have their affinity with the Ampelidece. 



The characters of the leaves of the Ampelidece, especially those of 

 C'issus, are somewhat obscurely represented in Sassafras Harkerianum 

 ("Cret. FL," pi. xi, figs. 3 and 4; pi. xxvii, fig. 2) and in S. obtusum (pi. xiii), 

 more distinctly in Cissites acuminatus (pi. v, fig. 3) and C. Heerii (pi. v, fig. 2), 

 .two new species described in this memoir. They appear to constitute an 

 indivisible group. Some of the leaves formerly described as Populites are 

 also referable to this section, or to another less exactly defined Ampelo- 

 phyllum, allied by some of its characters to Hedera, by others to Oredneria, 

 thus intermediate between the Avipelidce and the Tilicaceoe; by the areola- 

 tion this genus is related to Greviopsis, and also more distantly to Chon- 

 drophyllum of Heer, as remarked in the description. From this it is per- 

 ceivable that this Sassafras type, which at the beginning was regarded as 

 simple, well defined, and limited in its character, is, on the contrary, mul- 

 tiple, and representing forms which, from increased researches and dis- 

 coveries, indicate affinity to a number of different genera or orders of the 

 vegetaBle kingdom. 



The same remark is equally applicable to the leaves which have been 

 ■described in the "Cret. Fl." under the generic name of Proiophyllum. The 



CF2 



