580 MESOZOIC FLORAS OF UNITED STATES. 



A stratum at Dutch Gap in Virginia, where this plant was first found, 

 is full of multitudes of small fragments of it, each representing one or two 

 joints. I was in great doubt as to the true place of the fossil he named 

 PagiophyUum dubium, and with much hesitation placed it provisionally 

 in the genus Pagioph3'llum. He did not think the amount of material 

 on hand justified the formation of a new genus. As this plant probably 

 is not a PagiophyUum, it may well continue to bear the name given it 

 by Doctor Nathorst, and the name PagiophyUum dubium should be 

 dropped. It should not, however, be identified with Frenelopsis parce- 

 ramosa. A plant nearly allied to the latter, but probably a different 

 i>pecies, occurs in the Glen Rose strata. 



CORRELATION OF THE POTOMAC FORMATION IN VIRGINIA AND MARYLAND. 



The above report of Professor Fontaine on the fossil plants collected 

 in the Potomac formation since the appearance in 1889 of his Potomac 

 or Younger Mesozoic Flora furnishes a much better basis for correlating 

 the Maryland and Virginia beds of that formation than that which existed 

 at that time or at the later date (1895) when my memoir on the Potomac 

 formation appeared. In order, however, still more fully to appreciate 

 the advance thus made in our knowledge of the flora in the two States, 

 and to furnish a condensed view of the results, I have prepared the fol- 

 lowing table of distribution of the species enumerated in the report: 



