Page:The Journal of geology (IA journalofgeology21894univers).pdf/276

The first of these was described by Heer from the Kome beds of Greenland (Gault or Urgonian), but it also occurs in the Atane beds, which are correlated with the Cenomanian and have been supposed to be nearly equivalent to the Dakota Group. It has been found in the Kootanie deposits of British America, in a supposed Neocomian deposit at Cape Lisbourne, Alaska, and in the Amboy Clays at Woodbridge, New Jersey. It is also one of the few ferns that have been found in the Dakota Group, where, however, it is rare. Its evidence, therefore, considered by itself, would be to put even this uppermost deposit in the Lower Cretaceous, but this is overcome by that of the remaining forms. The specimens are the best in the collection, good and characteristic, leaving no doubt on the score of identity.

Quercus Wardiana Lx., is an exclusively Dakota form, but the specimens are too imperfect to make the determination sure.

Lindera venusta Lx., is a characteristic Dakota species, and one of the specimens leaves no doubt as to identity.

Aralia Towneri Lx., is also confined to the Dakota Group, but the specimens, though tolerably good, do not exactly agree, the lobes being too short. They most resemble the specimen figured by Lesquereux in his Flora of the Dakota Group, pl. xxxi, fig. 3, which he doubtfully refers to Sterculia Snowii Lx., but which does not at all resemble the type specimens of that species, and probably belongs to Aralia Towneri.

The leaf which I name Viburnites Evansanus^[1] is one of the best preserved in the collection, but it differs specifically from all the forms known to me. It is clearly of the type of Viburnites crassus Lx., and V. Masoni Lx., of the Dakota Group (Fl. Dak. Gr., pp. 124, 125; pl. xlv), but is longer in proportion to its width with a larger number of secondary nerves, which are irregularly disposed, the angle differing on the two sides of the midrib, as do also their number and proximity. The branching is strictly dichotomous and the finer nervation is distinct. The margin is only preserved near the summit, but here it is that of V. crassus.