lobes the nerves become one or more times forked, without a midnerve.'"' — 

 Fontaine, 1890. 



The foregoing description is that of Aspidium dentatum, but it applies 

 equally well to Aspidium micro car pum. It is curious that these two 

 supposed species, both present in the same outcrop and identical except 

 for the fact that in the one case they were sterile and in the other showed 

 traces of sori, should have been made the basis of two distinct species. 

 The reference of the Dutch Gap specimens here is not above question. 



Occurrence. — Patuxent Formation. Dutch Gap, near Potomac Eun, 

 Telegraph Station (Lorton), Virginia. 



Collection. — IT. S. ISTational Museum. 



Dryopteeites virginica (Fontaine) 



Aspidium virginicum Fontaine, 1890, Mon. U. S. Gaol. Survey, vol. xv, 



1889, p. 97, pi. XV, fig. 14. 

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



1889, p. 100, pi. xxi, fig. 5. 

 Dryopteris virginica Knowlton, 1898, Bull. U. S. Geol. Survey, No. 152, 



p. 93 (non Fontaine, 1906). 

 Dryopteris oMongifolia 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; pinnge of ultimate order reduced 

 to pinnules in the terminal portions of the penultimate pinnse, alternate, 

 linear-lanceolate, passing through pinnately lobed pinnse into pinnules 

 with entire margins ; leaf -substance thick and leathery ; nerves slender, 

 immersed in the leaf-substance, and seen with difficulty; pinnules of 

 the lower pinnae- opposite, separate to the base ; attached by the entire 

 base, elongate oblong, subacute, with denticulate margins; sterile form 

 of the frond not seen; sori comparatively small, reniform, in two rows, 

 one on each side of the midnerve of the pinnules, and placed at the sum- 

 mit of the upper branch of a forking nerve." — Fontaine, 1890. 



The description quoted is that of Aspidium virginicum^ but it fits the 

 species as emended here, the form previously described as Aspidium 

 oblongifolium being entirely inadequate for framing a description. The 

 two are clearly identical. The occurrence of this species at the locality 

 near Brooke, which is within the Patapsco formation, is queried, since 



