PALEONTOLOGIC NOTES — FLORA 173 



limestone is the first appearance of Callipteris conferta, he thinks the 

 lower limit may be drawn safely at that horizon. The flora of the upper 

 Dunkard is to be compared with the Stockheim and Cusel beds in Ger- 

 many and the series in the basin of Brives in France. None of the 

 characteristic coniferous genera, Ullmannia, Tylodendron, WalcJiia, oc- 

 curs in Dunkard beds, though all are in Prince Edward island and 

 Walchia is reported from Texas; and similarly many genera of ferns 

 characterizing the Eothliegende of Europe seem to be wholly unrep- 

 resented. 



In connection with Mr White's conclusions, it is well to recall some 

 relations noted in preceding pages. The general physical conditions 

 during Allegheny and Conemaugh were practically the same; for, while 

 the basin was contracting, there was no material variation in character 

 of the movements; but with the beginning of the Monongahela the area 

 of greatest subsidence was shifted a hundred miles and the new condition 

 remained unaltered throughout the Monongahela and "Washington, which 

 in this respect are one as the Allegheny and Conemaugh are one. A 

 notable change occurred at the Washington, and Mr White has shown 

 that the strongly marked lower Eothliegende flora makes its appearance 

 near the bottom of the Greene formation. 



After the publications in 1880, no others, aside from a supplement 

 to Mr Lesquereux's catalogue, appeared until 1894, when Mr White pre- 

 sented a discussion, which, like that by Fontaine and I. C. White, marks 

 a stage in the development of paleobotanic study within the United 

 States. In this paper * the term "Pottsville" is applied to beds extend- 

 ing from the base of the Pennsylvanian to and including the ISTuttall 

 sandstone, which passes under New river at Kanawha falls, this use of 

 the term being in accord with usage then prevailing for that region; it 

 is equivalent to Eockcastle. The discussion was based on study of col- 

 lections made by the author at 12 horizons whose relations were deter- 

 mined by his stratigraphic work along New river. He availed himself 

 of previous studies by Professor Fontaine and of collections made away 

 from the river by Mr M. E. Campbell, whose stratigraphic work left no 

 room for doubt respecting relations of the localities. 



The lowest two horizons seem to belong to the Mississippian, but the 

 third, at 375 feet from the bottom, yielded 4 forms characterizing the 

 Pocahontas coal bed at the Virginia- West Virginia line, 75 miles away. 

 Soon after this determination was announced, Mr Campbell proved the 

 stratigraphic equivalence of the horizons. The flfth horizon, that of 



* D. White : The Pottsville series along New river, West Virginia. Bull. Geol. Soc. 

 Am., vol. 6, pp. 303-320. 



XIII — Bull. Geol. Soc. Am., Vol. 18, 1906 



