502 MESOZOIC FLORAS OF UNITED STATES. 



The pinnules are narrowed toward the base and are expanded toward 

 the apex, mostly into two round lobes. A nerve passes into the base 

 of the pinnule and splits into two branches, one going into each lobe. 

 The branch in the upper lobe bears at its summit a club-shaped sorus. 

 These fructified forms are very rare. 



Eight of the specimens of this plant wei'e found at the White House 

 Bluff locality on May 14, 1893, and these include the largest ones, the 

 finest one being that represented by Professor Ward's fig. 3. The rest 

 were collected at the Mount Vernon locality on November 6, 1892, and 

 those represented by his figs. 1 and 2 are from there. The specimen now 

 figured (PL CVH,, Fig. 10) is from White House Bluff and occurs in the 

 same collection as the large one figured in the Fifteenth Annual Report. 



Sterculia elegans Fontaine ?. 



Pi. CX, Fig. 6. 



1889. Sterculia elegans Font.: Potomac Flora (Monogr. U. S. Geol. Surv., Vol. XV), 

 p. 314, pi. clvii, fig. 2; pi. clviii, figs. 2, 3. 



Sterculia elegans is a plant found at Deep Bottom, on James River, 

 on the horizon of the Aquia Creek group. It maj^ be present at the 

 Mount Vernon locality, represented bj^ a single specimen collected 

 November 6, 1892. This is a fragment of a leaf showing its basal por- 

 tion and a part of the petiole. In the leaf there are two main nerves 

 diverging from the top of the petiole. No central nerve, if ever present, 

 is now visible. Possibly the plant maj^ be a Bowenia. 



Thinnfeldia variabilis Fontaine." 



PL CX, Figs. 7, 8. 



1889. Thinnfeldia varialilis Font. : Potomac Flora (Monogr. U. S. Geol. Surv., 

 Vol. XV), p. 110, pi. xvii, figs. 3, 3a, 4, 4a, 5-7; pL xviii. 



This is a very rare fossil in the Mount Vernon beds. Onlj' two 

 specimens, showing small bits of ultimate pinnae, were obtained, both 

 from the White House Bluff locality, on June 23, 1896. 



"On the label Professor Fontaine queries the reference of these specimens to T. variabilis, but in his 

 manuscript he makes the reference positive. They were the only specimens I was able to find at the White 

 House Bluff locality when I visited it in company with Mr. Charles L. Pollard on June 23, 1896, or nearh' 

 three yeai-s after the principal collection was made. In my notebook I record that the conditions were much 

 changed by washing, and it is probable that the spot where the ferns were found was several feet farther in 

 the bluff than the original bed. As this fern was not found in the much larger collection previously made, 

 and does not seem to occur at the Mount Vernon locality, the finding of these specimens thus isolated is some- 

 what singular.— L. F. W. 



