OLDER POTOMAC OF VIRGINIA AND MARYLAND. 475 



known plant beds in Virginia. This evidence is put in more available 

 form in the table of distribution which I append to the report. 



Several years ago I was informed that the United States National 

 Museum was to undertake the publication of a revised edition of m}?^ 

 Guide to the Flora of Washington and Vicinity," bringing it down to 

 date and rearranging the matter to conform to modern ideas of classi- 

 fication and nomenclature. The different departments were to be 

 elaborated by specialists in each. I offered to revise the introductory 

 matter and to contribute a chapter on the fossil plants from all locali- 

 ties falling within the area covered by the original work. This, in brief 

 terms, extended from Great Falls on the north to Mount Vernon on 

 the south, and back from the river to the Piedmont Plateau on the 

 west and to the divide between the Potomac and Patuxent drainages 

 on the east. Of the localities treated in Professor Fontaine's report 

 now to be considered it would therefore have included the following: 



Langdon, D. C. 



Queens Chapel road, D. C. 



Rosiers Bluff (Fort Foote), Md. 



Riverdale, Md. 



Berwyn, Md. 



Bewley estate, Md. 



Muirkirk, Md. 



Con tee, Md. 



Mount Vernon. 

 Hell Hole. 

 Moutli of Hell Hole. 

 Chinkapin Hollow. 

 Sixteenth street, Washington, 

 New reServoii-, Washington. 

 Terra Cotta, D. C. 

 Ivy City, D. C. 



Some of these localities were unknown at that time, but I had 

 in my hands the collections from Mount Vernon, Chinkapin Hollow, 

 Sixteenth street, the new reservoir. Terra Cotta, Rosiers Bluff, and 

 Muirkirk, nearly as they are known at the present time. 



I set about, as time would permit, the determination of these col- 

 lections, and studied many of the specimens, giving names to several 

 new species and preparing a list of all the fossil plants that would belong 

 to the flora of Washington and vicinity. I intended to describe the 

 new species and to write the chapter, but learned that the publication 

 of the revised edition had been somewhat indefinitely postponed. I 

 therefore suspended work on these collections, and when the time came 

 for the general treatment of the Potomac flora for the present paper I 



oBuIl. U. S. Nat. Mus. No. 22, 1881. 



