262 Systematic Paleontology 



Description. — "Frond unknown; probably bipinnatifid ; reduced pin- 

 nse or pinnules, linear, cut pinnately nearly to the rachis into ovate-falcate 

 obtuse lobes or pinnules ; leaf -substance thick and leathery ; sori in a row- 

 on each side of the midrib, elliptical in shape and small, placed on the 

 simple lateral nerves within the margin of the lobes.''— Fontaine, 1890. 



This so-called species is based on very rare and fragmentary material 

 and is undoubtedly identical with other material referred to this genus 

 or to Cladophlehis. Professor Fontaine compared it with Didymoclilcena, 

 but it is absolutely worthless for either stratigraphic or botanical pur- 

 poses. 



Occurrence. — Patapsco Formation. Bank near Brooke, Virginia. 



Collection. — U. S. National Museum. 



Dryopterites cystopteroides (Fontaine) 



Asvidium cystopteroides Fontaine, 1890, Mon. U. S. Geol. Survey, vol. xv, 



1889, p. 99, pi. xvi, fig. 2. 

 Dryopteris cystopteroides Knowlton, 1898, Bull. U. S. Geol. Survey, No. 



152, p. 91. 



Description. — " Sterile fronds not seen ; rachis of ultimate pinnae 

 slender; pinnules alternate, attached by the middle portion of the base, 

 crenately toothed, obtuse; sori rather large, in two rows, one on each 

 side of the midrib, placed near the margin, on the summit of the upper- 

 most branch of the nerves; subglobose in shape, similar to those of 

 Cystopteris, with an inflated indusium at base; nerves branching palm- 

 ately in each tooth." — Fontaine, 1890. 



No new material is available for study. It is probably identical with 

 what is here called Dryopterites virginica. 



Occurrence. — Patuxent Formation. Fredericksburg, Virginia. 



Collection. — U. S. National Museum. 



Dryopterites elliptioa (Fontaine) 



Aspidium, ellipticum Fontaine, 1890, Mon. U. S. Geol. Survey, vol. xv, 1889, 



p. 95, pi. xiii, figs. 9, 10. 

 Dryopteris elliptica Knowlton, 1898, Bull. U. S. Geol. Survey, No. 152, p. 92. 



Description. — "Frond bipinnate or tripinnate, arborescent; rachis of 

 the principal pinna stout and rigid; ultimate pinuge alternate, short. 



