320 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



genus. This, more than any otliei' species of the genus, shows a markedly 

 comprehensive cliaracter. The general shape of the leaf and the position 

 of the lobes remind one strongly of Sassafras. It is also a good deal like 

 some species of Acer. The small outermost lobes are strikingly like those 

 of Liriodendron. Its generic affinities are with Aralia. 



HYMEN.EA L. 



The genus HijmeiKxa appears to be represented by one well-character- 

 ized species, which, however, so far as seen, shows very few individuals. 

 It sliould, however, be stated that most of the well-preserved species of 

 angiosperms from the 72d mile-post, near Brooke, such as those of Sassa- 

 fras, Aral'KcphyUam, Hijmencea, Menispermites, Hederaphijllum, etc., are ob- 

 tained from the thin la}er of well laminated clay before described. As 

 nearly all these plants are found nowhere but in this layer, and as the 

 amount of material olitained from it was very small, the apparent rarity of 

 these fossils may result solely from this fact, and statements concerning the 

 abundance of the specimens should be made with this qualification. 



HYMEN.EA ViEGINIENSrS, S]). nOV. 

 Plate CLXIII, Fig. 0. 



Upper part of tlie leaves not seen; towards the base they are narrowed 

 into an elliptical shape ; leaves in pairs at the simnnit of the petiole ; pet- 

 iole very strong ; midnerves of the leaves strong and prominent ; lateral 

 nerves not seen ; leaf-substance thick ; epidermis thick and glossy ; the 

 right-hand leaf is considerably larger than the left-hand one ; the midnerves 

 of the leaves do not run through the centers of the leaves, the outer portion 

 of the lamina being wider. 



Localit}^ : 72d mile-post, near Brooke ; rare. 



This plant is a good deal like Hijmencv.a primigenia^ Saporta, as figured 

 by Velenovsky, but the leaves are wider at base. 



ACERIPHYLLUM, gen. nov. 



This genus is formed to contain a species of comprehensive type which 

 stands nearer to Acer than to any other, but still differs too much to permit 



' Flor. Uer biihtn. Kreideform., pt. 2, PI. VI, Fig. 4. 



