504 MESOZOIC FLORAS OF UNITED STATES. 



FOSSIL PLANTS FltOM HELL HOLE. 



[PI. LXXX, No. 147.] 



On April 7, 1896, Mr. Arthur Bibbins collected for the Marjdand 

 Survey a considerable number of fossil plants from a locality called 

 Hell Hole, on the Virginia side of the Potomac River. This locality 

 is between Mount Vernon and White House Bluff,' but some distance 

 above Professor Ward's locality. Most of the rock matter is grajdsh 

 chocolate-colored, arenaceous clay, which preserves the plants fairly 

 well. Some is a chocolate clay. The following is the list of fossils 

 obtained here: 



Aristolochiffipliyllum crassinerve Font 2 specimens. 



Athrotaxopsis expansa Font 2 specimens. 



Baieropsis f oliosa Font 9 specimens. 



Baiei'opsis longifolia Font 1 specimen. 



Baieropsis pluripartita Font .3 specimens. 



Carpolithus virginiensis Font 1 specimen. 



Celastrophyllum brookense Font. ? 2 specimens. 



Cladophlebis constricta Font. ? ? 2 specimens. 



Ficophyllum tenuinerve Font. ? 6 specimens. 



Frenelopsis ramosissima Font. ? , 1 specimen. 



Leptostrobus longifolius Font 1 specimen. 



Menispermites virginiensis Font. 1 3 specimens. 



Onychiopsis psilotoides (Stokes & Webb) Ward 3 specimens. 



Sassafras bilobatum Font. ? 1 specimen. 



Sequoia ? inf erna Ward nom. nov 2 specimens. 



Sphenolepidium Sternbergianum densifolium Font 19 specimens. 



Thyrsopteris divaricata Font. 1 1 specimen. 



Baieropsis foliosa Fontaine. 

 PL CX, Fig. 9. 



1SS9. Baieropsis foliosa Font. : Potomac Flora (Monogr. U. S. Geol. Surv., Vol. XV), 

 p. 209, pi. xciii, figs. 4, 4a, o, 6, 6a. 



Nine specimens of this species occur at Hell Hole, but even the 

 best of them contain only a small portion of the plant. This is a spe- 

 cies highh' characteristic of the Aquia Creek horizon in Virginia. The 

 specimens from Hell Hole show lacinise even more slender than the 

 Virginia forms. PI. CX, Fig. 9, gives one of these. It bears the num- 

 ber M. G. S., 8431. 



