OLDER POTOMAC OF VIKCJINIA AND MARYLAND. 



543 



If we omit from the list of plants found at these localities the new 

 species and the doubtful forms, we have the following : 



Dryopteris fredericksburgensis. 

 Diyopteris parvifolia. 

 Gl^'ptostrobus (Taxodium) expansus. 

 Proteffiphyllum oblongifolium. 

 Sequoia ambigua. 

 Sphenolepidium Kurrianum. 



Abietites angusticarpus. 

 Athrotaxopsis expansa. 

 Athrotaxopsis tenuicaulis. 

 Brachyphyllum parceramosum. 

 Cladophlebis acuta. 

 Cladophlebis alata. 

 Dryopteris angustipinnata. 



These, with the exception of the last one, as described in Monograph 

 XV, are all confined to the horizon of the James River and Rappahan- 

 nock series, which form the lowest portion of the Lower Potomac of 

 Virginia. Sphenolepidium Kurrianum, though common in the lower 

 beds, also occurs in the Brooke beds at the 72d Milepost, and at the bank 

 near Brooke. But it is rare in the Arlington flora. These facts make it 

 most probable that the Arlington l^eds are of the age of the James River 

 and Rappahannock series, equivalent to the Arundel. 



KOSSIL PLANTS FKO-II HANOVER. 



[PI. LXXX, No. 48.] 



The collections from Hanover were all made by Mr. Arthur Bibbins, 

 for the Maryland Geological Survey, and bear labels accordingly. Twelve 

 specimens having determinable plant impressions were collected in June, 

 1896, and 1 in August, 1896, while 13 others bear no date. There is one 

 specimen without a label, the material of which is identical with that of all 

 but three of the others, and there can be no doubt that it is from the same 

 bed. This material is an ash-gray clay, filled with small specks of lignite 

 and other vegetable matter. Two of the specimens obtained in June, 

 1896, are of a different material, being lighter colored and sandy. These 

 bear the numbers 8604 and 8607. One other collected at that date is a 

 heavy ironstone of a bright-red color. This bears the number 8611. 

 The 13 specimens whose labels are not dated are all from the same clay as 

 the most of those that are dated. The specimens dated June, 1896, 

 other than the three already mentioned, bear the following numbers of 

 the State Survey: 8242, 8597, 8602, 8603, 8609, 8613, 8618, 8619, 8620. 

 The specimen whose label is dated August, 1896, is numbered: M. G. S,, 



