PLATE 37, FIGURES 4, 5 (6, 7?); PLATE 39, FIGURE 4
"Cissampelos?" Hollick, Summary Kept. (loc. cit.), p. 135.
Whether or not these leaves should be regarded as generically, or even as specifically distinct from Ccbatha multiformis, the species last described, may perhaps be an open question. The specimen upon which the original generic identification was tentatively based (loc. cit.) is represented by FIGURE 4 on PLATE 39, which may be compared with the existing species Cissampelos microcarpa De Candolle (or C. Pureira Linnaeus?), represented by FIGURE 5, PLATE 46, drawn from a specimen collected on the island of Hispaniola. The specimen represented by FIGURE 3, PLATE 46, is another one of the same species, collected in Porto Kico, and this may be seen to compare so closely with our specimens represented by FIGURES 4 and 5, PLATE 37, that generic relationship, at least, can hardly be doubted.
The fragmentary specimens represented by FIGURES 6 and 7, PLATE 37, may belong either with Cissampelos or with Cebatha, or with Menispermum, and their inclusion under Cissampelos dubiosa is to be regarded as open to question.
The genus Cissampelos does not appear to have been recognized in paleobotany previous to its identification as an element in the flora of the Saint Eugene silts, hence there are no available descriptions or illustrations of any fossil forms with which comparisons with our specimens may be made. In order that the difficulty attaching to any satisfactory generic identification of our specimens may be appreciated I have introduced (see PLATE 46) figures of leaves of Cebatha Carolina (FIGURES 1 and 2), Cissampelos Pareira Linnaeus? (FIGURE 3), Cissampelos fasciculata Bentham (FIGURE 4), Cissampelos microcarpa De Candolle (FIGURE 5), Menispermum canadense Linnaeus (FIGURE 6), and M. diver si folium (Miquel) Prantl.
In the Old World a fossil species that compares very closely with certain of our specimens is Cocculus latifolius (Saporta) Saporta & Marion29 ( = Menispermum latifolium Saporta), from the Pliocene of France. A comparison of our FIGURE 1, PLATE 38, with Saporta's figure 6, plate 31 (loc. cit.), shows a somewhat striking resemblance; and it is of interest to note that Saporta also had difficulty in deciding betwreen the genera Menispermum and Cocculus ( = Cebatha), as to which one his species should be referred.
Incidentally, comparison may also be made between the lobed and lobate-dentate forms in our collection and certain leaves from the Miocene of Washington, described and figured by Knowlton30 under the names Populus heteromorpha and P. Fairii, several of which present a remarkable resemblance to our FIGURES 3 and 4, PLATE 38, and FIGURE 1, PLATE 39, but whether or not there is any special significance in connection with this resemblance I would not venture to infer or suggest.