480 MESOZOIC FLORAS OF UNITED STATES. 



plant which is common at that locaUty and which was ah'cady known 

 from that region, ):)eing descnl)ed in Monograph XV, p. 182. The plant 

 is characteristic of the lowest portion of the Lower Potomac of Virginia, 

 the James River and Rappahannock series in the subdivisions of Pro- 

 fessor Ward. The specimen represented on PI. CVII, Fig. 2, is not 

 numbered; that shown on PI. CVIII, Fig. 1, is No. 5716 of the museum 

 of the Woman's College of Baltimore. 



One other leaflet of this plant occiu's in a collection made by Mr. 

 Ira Sayles from the Sailors Tavern locality on September 22, 1886. 



KOSSII, I'LAMS KlidM AUM KOCK. 



The locality called Alum Rock is about 2 miles southwest of Fred- 

 ericksburg. The material here that yields the fossils is a sandy shale, 

 with \'eiy imperfect cleavage. It is near the base of the Lower Potomac, 

 belonging to the lower portion of the Rappahannock or Fredericksburg 

 series of strata. The fossils are few and poorly preserved, being mostly 

 small fragments which can not be identified. The following species 

 occur in the collection made by Messrs. Ward and White on May 3, 1892: 



Carpolithus virginiensis Font_ _ 1 specimen. 



Cladophlebis alata Font 1 specimen. 



Cycadeospennum acutum Font 1 specimen. 



Pecopteris virginiensis Font 3 specimens. 



Sphenolepidiimi Sternbergianum densifolium Font 1 specimen. 



Mr. Bibbins also collected some specimens for the Maryland Survey 

 from Alum Rock, but none of them are determinable. 



FOSSIL PLANTS FK(»M THE 72D MILEPOST. 



The locality designated "72d Milepost," on the Richmond, Fred- 

 ericksburg and Potomac Railroad, which is a link in the Atlantic Coast 

 Line system, is described in Monograph XV, pp. 19-20. The fossils 

 found there were mostly in redeposited material, composed of clay lumps 

 embedded in the sand in a short cut. The clay contained nearly all the 

 plants. It must have been torn up and redeposited soon after its original 

 deposition, so that both events l)elong to the same geological time. It 

 belongs to the Aquia Creek series of Professor Ward's grouping of the 

 Lower Potomac. 



There are in the Maryland Survey collections a number of fossils 

 credited to a locality given on the labels as "Railroad cut south of Aquia 



