OLDEH POTOMAC OF VIRGINIA AND :\IAHYLANI). 517 



locality on the day iianunl Ix^lonfi to the fofii Tln/rsoptcn's rarincrvif;, Init 

 some tubers of E<iuisekim )narylari(licinn and some othci' Thyrsoptoris 

 forms also occur. The plants from the locality on the west side ai-e all 

 different from these, no ferns having been found tli(>re, but a cone piobably 

 of S])hcuol('j)i(linr)i virgu)iru)n, a leaf of Dioortitcs Jinclii(i)nis.\ and one of 

 Baicropnis loiigifolia were found. 



On October 2, 1S92, Professor Ward and Doctor Hollick coHccKmI at 

 the fii'st-named locality a number of specimens, but iieaily all of them 

 belong to Equiselum marylandicum. 



On .bdy 7, 1893, I went to this same place witli Professor Ward and 

 we secured a few specimens, Imt they were mostly diffei-ent from any 

 previously collected, including a species of Brachyphyllum. This shows 

 that the different clay seams hold different plants, and that the flora of 

 these beds is very rich and varied. 



The following species o(H'ur in all these collections : 



Baieropsis longifolia Font 1 specinicn. 



Brachypliyllum ])iUToramosum Font. ?. 3 sppcimciis. 



Cladoplili'liis Browniana (Dunk.) Sew . 1 spociiiK'H. 



Dioonitcs Buchianiis (Ett.) Born.? : 1 specimen. 



Equisctuni niarj-landicum Font . 19 specinien.s. 



Onyclii()|)sis psilotoidos (Stokes & Webb) Ward 1 specimen. 



Sphen()le|)i(lium virginicum Font.? 1 specimen. 



Thyrsopteris densifolia Font ] specimen. 



Tliyrsoptcris divaricata Font. ? 2 specimens. 



Thyrsopteris eliipt ica F'ont 3 specimens. 



Thyrsopteris nervosa Font 3 specimens. 



Thyrsopteris rarinervis Font _ (50 specimens. 



Zamiopsis insignis Font. ? 1 specimen. 



Most of the specimens from the new reservoir seem to have been 

 reduced to small fragments, but in many cases they are pretty well pre- 

 served, for the leaf substance is often retained 



Equisetum marylandkutm Fontaine. 



PI. (TX, Fig. 10. 



1889. Equisetum marylandicum Font.: Potomac Flora (Monogr. U. S. Geo!. Surv., 

 Vol. XV), p. 6.5, pi. ii, figs. 10, 10a. 



This species stands second in abundance at this locality, and a good 

 many specimens were obtained. It is a peculiar fact that nearly all of 



