NO. 1862. FOSSIL FERNS FROM THE POTOMAC GROVP— BERRY. 311 



Cladophlehis inclinata Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 76, 



pi. 10, figa. 3, 4; pi. 20, fig. 8. 

 Cladophlehis denticulata Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 71, 



pi. 4, fig. 2; pi. 7, fig. 7 (not Nathorst). 

 Cladophlehis, sp., Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 77, pi. 10, 



figs. 5, 8; pi. 20, fig. 7. 

 Cladophlehis pachyphylla Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, 



p. 80, pi. 25, fig. 9. 

 Cladophlehis, sp., Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 77, pi. 15, 



fig. 6; pi. 19, fig. 3. 

 Aspidium angustipinnatum Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, 



p. 98, pi. 16, figs. 1, 3, 8; pi. 17, fig. 1; pi. 19, fig. 10. 

 Dryopteris angustipinnata Knowlton, Bull. 152, U. S. Geol. Surv., 1898. — Fon- 

 taine, in Ward, Monogr. U. S. Geol. Surv., vol. 48, 1906, pp. 540, 544, 548, 



pi. 114, fig. 6. 

 Aspidium oerstedi f Fontaine, Monogr. 15, U. S. Geol. Surv., 1890, p. 99, pi. 19, 



fig. 4 (not Heer). 

 Dryopteris oerstedi ? Knowlton, Bull. 152, U. S. Geol. Surv., 1898, p. 92. 



Description. — A large amount of material has been referred to this 

 species since Dunker's day, so that his diagnosis may be considerably 

 amplified. In general these forms show the following characters: 



Fronds large, bipinnate or tripinnate. Rachis stout. Pinnae linear 

 lanceolate, alternate to subopposite, becoming pinnatifid distally. 

 Pinnules usually attached by their whole base, which is slightly 

 expanded, contiguous but usually separated to the base, lanceolate, 

 slightly falcate, acuminate. Margin usually entire, more rarely 

 somewhat dentate in the apical portion. Venation of the usual 

 CladopMehis type. Fertile fronds have the racliis more slender 

 than in the sterile fronds. The sori are borne on a distal branch of a 

 furcate vein, as in other Potomac species of Cladophlehis, and form a 

 row on either side of the midvein of the pinnules, which are otherwise 

 indistinguishable from the sterile pinnules, though inclined to be 

 straighter. 



This species has been made to include a large amount of material 

 from various horizons and localities which in the first instance was 

 described as various species of Neuropteris, Aleihopteris, Pecopteris, 

 Pteris, etc. It is not at all certain that the result may not be a com- 

 posite species made up of several distinct species with indistinguish- 

 able vegetative characters, and it would not be difficult to select still 

 other forms from various parts of the world which could scarcely be 

 separated from the foregoing. 



Cladophlehis alhertsii was not recognized as such in Professor 

 Fontaine's Potomac studies, but it is obvious that the forms described 

 as CladopMehis inclinata and Cladophlehis denticulata (this was 

 described as a new species and is decidedly different from Bron- 

 gniart's species of the same name which Nathorst has referred to 

 Cladophlehis) and as Aspidium angustipinnatum are identical with 



