WEST VIRGINIA GEOLOGICAL SURVEY 39I 



on preliminary examinations and are tentative, the collections hav- 

 ing 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 cover- 

 ed by the "IMillstone Grit", and the Lower Coal Measures of Great 

 Britain, the Beaver River group being referable approximately to 

 the Middle Coal IMeasures 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 AVestphalian age, the higher Penn334vanian beds 

 being of Stephanian age as these periods are defined in Con- 

 tinental 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 A\'"ashington 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 fr-^'m beds in the Alle- 

 gheny 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 identifica- 

 tions of a number of geologists and paleontologists and represent 

 not merely the work of different men but also the work of differ 

 ent periods or stages in the growth of our knowledge of the; 



