NO. 1862. FOSSIL FERNS FROM THE POTOMAC GROUP— BERRY. 329 



low, Virginia; Fort Foote, near Glymont, Vinegar HUl (?), Federal 

 Hill (Baltimore), Maryland. 



Collection. — United States National Museum, Maryland Academy 

 of Science, Goucher College. 



ONYCHIOPSIS BREVIFOLIA (Fontaine). 



Thrysopteris brevifolia Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 121, 



pi. 24, figs. 5, 10.— Fontaine, in Ward, 19th Ann. Kept. U. S. Geol. Surv., pt. 



2, 1899, p. 660, pi. 161, figs. 10-15. 

 Thrysopteris dentata Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 121, 



pi. 24, figs. 4, 6, 7, 9; pi. 25, figs. 1, 2. 

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



p. 135, pi. 50, fig. 3. 

 Thrysopteris nana Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 141, 



pi. 56, figs. 4, 8. 

 Thrysopteris heterophylla Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 142, 



pi. 58, fig. 3. 

 Thrysopteris sphenopteroides Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, 



p. 143, pi. 58, fig. 6. 

 Thrysopteris squarrosa Fontaine, Monogr. U. S. Geol. Surv., vol. 15, 1890, p. 143, 



pi. 59, fig. 3. 

 Thrysopteris retusa Fontaine, Monogr. U. S. Geol. Sui'v., vol. 15, 1890, p. 144, 



pi. 59, fig. 10. 



Description. — Frond small, bipinnate or tripinnate. Rachises 

 rather slender, often winged. Pinnae alternate to subopposite, rela- 

 tively long and narrow, divided below, pinnatifid distad. Pinnules 

 much narrowed at the base, decurrent, obliquely toothed or divided, 

 the extent depending upon their position on the frond, triangular 

 ovate to lanceolate in outline. Veins somewhat fiabellate, once or 

 twice forked or simple. Texture coriaceous. 



This species is not common in the Potomac and is confined to the 

 basal beds in the Virginia area, although it has also been reported 

 from the Lakota formation in the Black Hills region and from the 

 Kootenai formation of Montana. It is represented in the Vu'ginia 

 area by quite a large number of mostly fragmentary specimens show- 

 ing slight variations in the character of the pinnule lobes or teeth 

 which were made the basis for distinguishing eight species by Prof. 

 Fontaine. It is possible that more than one type is included in the 

 species as defined by the writer, the nature of the material rendering 

 certainty out of the question; but if the test of the validity of a 

 species be the possibility of its being recognized a second time by 

 either the original author or other students it must be adrcitted that 

 these eight so-called species are not good species. 



Onchiopsis hrevifolia dift'ers from OnycMopsis goepperti and psilo- 

 toides principally in the smaller fronds, less robust pinnules, which 

 are also less ascending, and in the much less elongate character of the 

 pinnas and especially the pinnules. It is a much smaller and less 

 robust form than OnycMopsis latiloha, from which it is readily dis- 

 tinguished, but approaches somewhat close to Onycliiopsis nervosa. 



