r)12 JHESOZOIC FLORAS OF UNITKI) STATES. 



Clapophleris virginiexsis Fontaine. 



PI. CXI, Fijr. 7. 



ISSO. Claclophlehis rirginiensis Font.: Potomac Flora (Monogr. U. S. Geol. Siirv., 

 Vol. XV), p. 70. pi. iii. fi<;.-<. 'S. 4. 4a. ;'>. .5a, 6, 7. 7a, S. Sa : pi. iv. figs. 1, la, 

 3, 3a, 4. 4a. 4b, .5, 6. 



Thi.s plant i.s not common, only 2 specimens occiiirino;. One of these 

 is a fragment of penultimate pinna with a rachis 5 mm. wide. It shows 

 the basal portions of two ultimate piiina^ which carry very large pinnules. 

 These show, toward their tips, a slight dentation, a feature not often seen 

 in the specimens previously found. It is shown on PL CXI, Fig. 7, of this 

 paper. 



Dryopteris fredericksburgexsis (Fontaine) Knowiton. 



PI. CXII, Fig. 2. 



1889. Aspulium fredericJcsburgense Font. : Potomac Flora (Monogr. U. .S. Geol. 

 Surv., Vol. XV), p. 94, pi. xi, figs. 1, la, 2, 2a, 2b, 3, 3a, 4, 4a, 5; 6, 6a. 



1898. Dryopteris fredericlsburgense (Font.) Kn.: Bull. U. S. Geol. Surv., No. 152, 



p. 92. 



Five specimens of this species were collected, 4 on April 16, 1893, and 

 1 doubtful one on July 17. The best specimen is a well-preserved por- 

 tion of a penultimate pinna with the basal portions of several ultimate 

 pinnae. These carry many pinnules. It is the form with entire pinnules, 

 and is shown in PI. CXII, Fig. 2, of this paper. 



Frexelopsis ramosissima Fontaine. 

 PI. CXI, Fig. S. 



1899. Frenelopsis ramosissima Font.: Potomac Flora (Monogr. U. S. Geol. Surv., 



Vol. XV), p. 21.5, pis. xcv-xcix; pi. c. figs. 1-3: pi. ci, fig. 1. 



This species yields 7 specimens, some of them good. The most com- 

 plete one is composed of several antepenultimate twigs, carrying a number 

 of penultimate ones. These have a number of ultimate twigs, all pretty 

 well preserved. This is shown in PI. CXI, Fig. 8. This fossil is highly 

 characteristic of the Fredericksburg or Rappahannock horizon in the 

 Potomac flora, l)eing practically confined to it. It is, then, important as 

 indicating that the Chinkapin Hollow horizon is the same. 



