FLORA OF OLDER POTOMAC FORMATION. 373 



these forms, which were the earUest obtained from the formation, it is 

 of interest to see precisely what they were, so far as can be ascertained 

 without access to the specimens themselves, whqse whereabouts is now 

 unknown, if, indeed, they were preserved at all. I therefore give the 

 list with the names used by Taylor, his figures, and Professor Fontaine's 

 identifications : 



Lycopodiolithes ? sp. Taylor: Trans. 'Geol. Soc. Pennsylvania, Vol. I, Phila- 

 delphia, 1835, p. 321, pi. xix, fig. 2. Probably a cast or stem of Frenelopsis ramosis- 

 sima Font. 



Lepidodendron sp. Taylor: Ibid., p. 322, fig. 1. Sphenolepidiiim Sternberg- 

 ianum (Dunk.) Heer. 



Sphenopteris sp. Taylor: Ibid., fig. 3. Scleropteris elliptica Font. 



Pecopteris ? sp. Taylor: Ibid., p. 323, fig. 4. Cladophlebis constricta Font. 



Thuites ? sp. Taylor: Ibid., fig. 5. Sphenolepidiiim dentifolium Font. 



Sphenopteris sp. Taylor: Ibid., fig. 6. Cladophlebis constricta Font. 



In May, 1891, I resumed the study of the Potomac formation, 

 assisted to a considerable extent by Mr. David White, and accompanied 

 on some of the excursions by Mr. Robert T. Hill, Prof. P. R. Uhler, and 

 others. On June 13 I discovered the important localit}- for fossil plants 

 in Rosiers Bluff, above Fort Foote, and made the first small collection 

 from there. The exact locality is 200 yards below Notley Hall wharf, 

 on the Fort Foote reservation. The clays rise here about 60 feet above 

 the river and occupy in the highest place all but a few feet of cobble and 

 surface gravel. They are varied in color, largely variegated red and 

 white, but often with more or less lenticular layers of blue, brown, and 

 darker. They are interstratified with sand, gravel, and ferruginous 

 shales. The plants were found about 30 feet above the water, in a thin 

 stratum of bluish clay, between two seams of coarse sand. 



On June 20 I made the following section of the exposure discovered 

 by me in 1885 near Aquia Creek, from which so many dicotyledonous 

 forms were subsequently collected, and which is designated by Professor 

 Fontaine in his monograph as "Bank near Brooke:" 



Section of the banlc near Brooke. 



Feet. 

 4. Fine-grained and laminated white, blue, and buff clays yielding the fossil plants and extending to the 



roots of the small trees, shrubs, and herbage covering the hill. ; 12 



3. White ferruginous sands, frequently cross-bedded, with very little interstratified clay, covered at the 



base, but traceable to near the bottom of the ravine 24 



2. Pack sand in gulch at bottom of ravine ■ 2 



1 . Whit e clay streaked with pink and red at bottom of gulch 2 



Total exposure 40 



