100 THE POTOMAC OR YOUNGER MESOZOIC FLORA. 



of the fern. It may be compared with tliat shown in Vol. VII of Heer's 

 work just cited, PL XLVIII, Fig. 11. 



ASPIDIUM OBLONGIFOLIUM, Sp. nOV. ? 

 Plate XXI, Fig. 5. 



Pinnules oblong, slightly falcate, acute, dentate; sori in a row on 

 each side of the midnerve, on the summits of the single lateral nerves, 

 round to broadly elliptical in shape, comparatively large. 



Locality: Road side near Potomac Run; very rare. 



This is an Aspiclium of the Didymochloena type. It may belong to 

 some of the elsewhere described Potomac forms. 



ASPIDIUM PARVIFOLIUM, Sp. nOV. 

 Plate XXI, Fig. 6 ; Plate XXIV, Fig. 8 ; Plate XXV, Fig. 10 ; Plato XXVI, Figs. 1, 14, 16, 17. 



Frond bipinnate to tripinnate; ultimate pinnae alternate; pinnules, or 

 reduced pinn;e alternate to opposite, in the sterile portions small, oblong- 

 lanceolate, acute, with winged rachises, pinnules or reduced pinn* of the 

 lower pinnte cut into ovate small lobes, the lowest ones being minutely 

 toothed, the upper pinnules also minutely toothed ; nerves of the lowest 

 lobes or teeth composed of a midrib, wliich sends off on each side, alter- 

 nately, simple nerves; in the upper lobes and teeth they are furcate; leaf- 

 substance thin, and usually decurrent ; in the fertile portions the pinnules 

 or reduced pinna^. are ovate-oblong, obtuse, with ovate-acute lobes, the two 

 lower being slightly dentate ; nerves in the lower lobes simple, and alter- 

 nately given off on each side of a slender midrib, those in the middle and 

 upper lobes several times or simply forked ; in the sterile forms the basal 

 upper lobe of the pinnules or reduced pinnae usually larger than the others 

 and directed upwards parallel with the penultimate rachis ; sori subglobose 

 in the two basal lobes and situated on the summit of the midrib and of all 

 the lateral nerves, but in the higher lobes mostly single in each lobe, and 

 placed on the summit of the upper branch of the lateral nerves. 



Localities: Fredericksburg; red clay ball in the banks of the Dutch 

 Grap Canal ; fishing hut above this canal ; rather rare at all places. 



This is an Aspidium of the Polystichum type. It does not seem to 

 be near any described plant. 



