DESCKIPTION OF THE SPECIES. 147 



size, very thick and leathery, apparently consisting ol" a midrib, Nvhich has 

 on each side a narrow thickened lamina, bearing on the margins large fruit- 

 masses rounded in form. 



Locality : Ilill-side near Potomac Ituu. 



The fertile forms are very rai-e at this locality, but the sterile ones are 

 very abundant, and much the most common of the specimens found here. 

 The form depicted in PI. LX, Fig. 5, I regard as the fructified form of the 

 fern which is described above, and which shows so many well-preserved 

 sterile specimens. As, however, the sterile and the fructified forms were 

 not found connected together, the union can not be taken as certainly 

 authorized. Unfortunately the fructification is not well enough preserved 

 to render its details clear. Fig. 5 gives the appearance as seen in natural 

 size with the unaided eye. Fig. 5'' gives the appearance under a lens. 

 The apparent fruit-masses look like rounded masses of naked sori or 

 sporangia. The entire fructified pinnules are so much thickened and so 

 poorly preserved, that nothing but the rounded shape and granular appear- 

 ance of the fruit-masses can be made out. Each mass of fruit seems to 

 represent a contracted and modified pinnule or lobe. The metamorphosis 

 of the pinnules reminds one of OsmumJa more than of a,i\Y other li\ing 

 genus, and I place the plant provisionally in this genus. Possibly this 

 may be a new genus, composite in character, which has some of the 

 features of Thyrsoptcrls and Osniunda, for there is an indication of a cup- 

 shaped grouping in the fruit dots. It is strange that no specimen of this 

 plant was found on the road-side near by. 



OSMUNDA DlCKSONIOIDES, var. LATIPENNIS, sp. nOV. 

 Plate LX, Figs. 1, 3 ; Plate LXI, Fig. 3. 



Frond tripinnatifid, large, arborescent; rachises proportionally slender; 

 pinnai and pinnules alternate ; rachises of the vdtimate pinna' narrowly 

 winged ; pinnules with membranaceous leaf-substance, short, oblong in 

 shape, and acute, attached b}- the middle point of the narrowed base, cut 

 more or less deeply into rounded, subquadi'ate, or broadly oval lobes, the 

 lower ones of which have shallow, subacute teeth ; fructified form not 

 seen. Nerves in each lobe remote, strong, composed of a nerve-bundle 



