490 MKSOZOK^ Kl.OKAS OF UNITED STATES. 



It is somewhat remarkable that these sliould pi'uve to he the only 

 specimens occurring in the later collections treated in this i)aper. None 

 were found at White House Bluf^". whei'e \hc oi'iginal types were ol)tained 

 and where the plant was the most common conifer. 



ntSSlI, PLANTS KHOM TIIK JKK'.NT VKK\(»N ItKDS. 



.\s intimated in the preceding account of the Acjuia Creek plants of 

 White House and Mount Vernon bluffs, the horizon of the Mount Vernon 

 series of V)eds is below that of the Aquia Creek series. Prof. Lester F. 

 Ward, who discovei'ed this horizon, has given an account of it and of 

 some of its plants in a paper entitled "The Potomac Formation."" This 

 paper may be consulted for descriptions of the localities from which the 

 collections of plants were made and of certain of the plants. 



Collectioi:ts were made from two localities on the Mount Vernon 

 horizon. One of these is the White House Bluff, while the locality first 

 discovered is higher up the river, above the mouth of Doag Creek. The 

 latter locality, for distinction, may l)e called "Ward's first locality," 

 while the other may be designated "Ward's second locality." The two 

 localities are on exactly the same horizon. It should be stated that the 

 first locality has yielded much the larger variety and quantity of plants. 



The following is the history of the collections from these localities: 



1. On October 16, 1892, Prof. Lester F. Ward discovered the priiicipiil locality, 

 viz, that above the mouth of Doag Creek, on the Mount Vernon estate. The exact 

 spot is opposite the site of the old Fairfax mansion and directly under the high point 

 once known as Roses Delight.'' Only a small collection was made on that day. 



2. Professor Ward visited the locality on November 6, 1892, accompanied by 

 Mr. Victor Louis Mason, prepared to make a much larger collection, in wliich they 

 were successful. 



3. The jiarty last mentioned discovered the Mount Vernon chocolate clays in 

 the White House Bluff on December 5, 1892. Only one specimen, however, was 

 collected on tliis occasion. 



4. On May, 14, 1S93, Messrs. Ward, Mason, and Hunter made an excursion 

 to both of these localities and brought back a large collection. 



5. I accompanied Professor Ward to the origuial Mount Vernon locality on 

 Julv 2.5, 1893. It was then mucli altered, the overhanging clay beds having fallen 

 and buried it under talus. Only two s])ecimens were obtained, as we had no facilities 

 for uncovering the l)ed. 



«Fifteenth Ann. Kept. U. S. Geol. Surv., 1895 (see pp. 324-325, 348-366, pL ii-iv). 

 bSee Fifteenth .\im. Kep. U. S. Geol. Surv., 1895, p. 325. 



