OLDKH POTOMAC OF VlHCilXIA AND ?kIAKVI.AM). 561 



street, near I'edei'al Hill, Icnvost "vein" in Weaver's elay i)it. The 

 rock inattcM- eariyin.ii the imprint is diCferent IVoin that hol(lin,<>; tlie 

 Acroslichopteris on .laelcson street and indicates a different hoi'izoii. 

 Tt is not the frial)le sandy cl.ay cariyin<!; Acrostichopteris, hut a plastic 

 ash-<iray cl.ay, like some of that common in the Lower Potomac of 

 Virjiinia on the horizon of the Rappahannock or Fredericks! )ur,i!; sti'ata. 



Seven specimens of A', cnniusfifolin occur in Mi'. Hihbin.s's collec- 

 tions from Federal Hill. One of these is a good imprint of a hit of a 

 pemiltimate twit:, and the I'cst are fragments of ultimate twigs with 

 poor leaves. 



It is a noteworthy fact that this species of Xageiopsis in the Vii-- 

 ginia Potomac shows generally much better preserved and more entire 

 forms than do the otlier species of this genus. 



Nageiop.si.s iieteropiiyll.v Fontaine. 



PI. CXVW. Fi-. n. 



ISSO. Nogeioj)sis heferophylhi Font.: Potomac Flora (Monogr. U. S. Geo). ,Surv., 

 Vol. XV), p. 201, pi. Ixxxiv, %. 4: pi. ixxxvi, fig,s. 6, (ja, 7; pi. Ixxxviii, 

 figs. 2, 2a, 5. 



This species is represented in the Covington and Clement streets 

 collections 1)>- 4 specimens. One of these, occurring in collection No. 5, 

 is an imprint with a numl:)er of good leaves that are suddenly dimin- 

 islied in size toward the end of the twig. It is shown in PI. CXVII 

 I'ig. 0, and is W. C, B., No. 5987. While A' . nngustifoUa is more com- 

 mon in the upper or Aquia Creek portion of the Lower Potomac in 

 Virginia, this species is there confined to the lower poi-tion of it. 



Genus PLANTAGINOP.SIS F.mtaine n. gen. 



Characters of the type species described below. 



Plant.\(!1nopsis marylandica Fontaine n. sp. 



PI. CXVH, Fig. 7: PI. CXVIII, Figs. 1,2. 



Among the specimens in collection No. 8, obtained at Covington 

 and Clement streets, certain impressions are found, o in munlx-r', that 

 seem different from any of the rest occurring here and which indicate 

 the existence of a new genus and species. They occin- sparingly- and 



.MON .xi.viii — 0.5 36 



