Page:The Living Flora of West Virginia and The Fossil Flora of West Virginia.pdf/415

Rh on preliminary examinations and are tentative, the collections having in a large number of cases not yet been fully studied.

The differentiation of the floras of the lower Pottsville which Doctor White has called the Pocahontas group; of the middle Pottsville, which he has termed the New River group ; and of the upper Pottsville for which he has adopted the name, Beaver River group, is fairly well established. As initial, or invasion, stages the Raleigh sandstone and the Nuttall sandstone lentil of the Sewell formation are logically placed by the writer in the New River and Beaver River groups, respectively, of Dr. White. His Pocahontas and New River groups fall within the time covered by the "Millstone Grit", and the Lower Coal Measures of Great Britain, the Beaver River group being referable approximately to the Middle Coal Measures and the "transition" series of Great Britain, while the Allegheny goes, for the most part, together with the Conemaugh and Monongahela, into the Upper Coal Measures of Great Britain. The beds up to an horizon possibly as high as the base of the Kittanning group of the coals in the Allegheny formation are of Westphaiian age, the higher Pennsyivanian beds being of Stephanian age as these periods are defined in Continental Europe.

The Dunkard formation, the division originally proposed by Doctor White in substitution for the "Upper Barren Measures" of the Pennsylvania State Reports, is here used for convenience and conformity with the West Virginia state nomenclature in place of Washington and Greene, the two formations into which the Dunkard has been divided.

The thanks of the writer are due to Doctor White and the other geologists of the State for the stratigraphic references of several of the fossil plant collections made from beds in the Allegheny and Conemaugh formations, the precise stage of these beds not having been determined prior to the detailed areal work now in progress by the State.

Among the species in the list there are many that have not been recorded from localities outside of West Virginia, though most are known to occur in beds of the same age in other parts of the Appalachian coalfields. In order, however, to avoid the description of new species which must necessarily be accompanied by illustrations, thus unduly increasing both the volume and the expense of publication, the list is confined to species already re ported from West Virginia, or—as in the cases of Lewis Tunnel in Virginia, or Brown's Mills and Jollytown in Greene County, Pennsylvania—from localities near the state boundary.

The names inscribed in this list are based upon the identifications of a number of geologists and paleontologists and represent not merely the work of different men but also the work of different periods or stages in the growth of our knowledge of the