266 Systematic Paleontology 



sterile pinnules linear-lanceolate, subacute, lower ones very long, much 

 diminished in length in ascending, cut more or less deeply into crenate 

 and rounded teeth and lobes ; lateral nerves in each lobe flabellate diverg- 

 ing, -with the branches forked or simple, nerves very strong and distinct; 

 fertile pinnae or pinnules very long, with strong, rigid rachises, linear, 

 subacute; lobes or teeth reduced to thick leathery supports, which bear 

 the narrowly elliptical son on the anterior face; the sori very long, al- 

 most as long as the lobes, standing one in each lobe, apparently included 

 between the two branches of a nerve that forks at the insertion." — Fon- 

 taine, 1890. 



The foregoing description should be modified by eliminating the fan- 

 cied thick soral peduncles which do not exist. As Professor Fontaine 

 has pointed out there is no adequate proof that the sterile and fertile 

 specimens belong to the same species. The species is an insignificant 

 element in the oldest Potomac, and none other than the type material 

 has been collected. The accompanying plate is from a photograph of 

 the specimen which formed the basis for Fontaine's idealized fig. 6 on 

 pi. xxii of the Potomac flora (loc. cit.). The specimen is poor, the 

 matrix being coarse, and the fern is represented by a brownish impres- 

 sion showing merely the outlines. No minute characters or spores could 

 consequently be made out. 



In some respects the fertile pinnae suggest those of Onychiopsis, the 

 pinnules are less reduced, however, and the sori appear to be single. The 

 sori are thick and about 3 mm. in length by a trifle under 1 mm. in 

 width. 



This species was doubtfully listed from the Shasta by Diller and 

 Stanton in 1894,* and by Stanton " in 1896, on the authority of Profes- 

 sor Fontaine, who afterward described the material as a new species of 

 DicJcsonia.^ 



Occurrence. — Patuxent Formation. Fredericksburg, Virginia. 



Collection. — U. S. ISTational Museum. 



^ Diller and Stanton, Bull. Geol. Soc. Am., vol. v, 1894, p. 450. 

 ^ Stanton, Bull. U. S. Geol. Surv., No. 133, 1896, p. 15. 



•'Fontaine in Ward, Mon. U. S. Geol. Surv., vol. xlviii, 1906, p. 224, pi. Ixv, 

 fig. 1. 



