latitude, Fiskaerness in Greenland {Dr. Sutherland ); it continues 
south as far as New York and Wisconsin, and is stated by Dr. 
Asa Gray to be frequent in exposed rocks in the middle United 
States, far from any mountains, and further south to the Alle- 
ghanies, but there in the mountains {Chapman). 
In general, with well-developed specimens, there is no difficulty 
in distinguishing this species from W. litjperborea ; it is more 
erect, more firm and rigid, much more paleaceous, and the scales, 
more or less broad, are ferruginous and often so copious as to give 
a reddish tinge to the whole frond, whence Michaux’s appropriate 
name, Neplirodium rufidulum; the pinnae are more elongated, 
more deeply pinnatifid (so as to be almost again pinnate) with 
much narrower and more oblong segments. Still I have many 
specimens so intermediate that myself and others have found it 
difficult to pronounce satisfactorily upon them. I have wavered 
in my opinion as to their distinctness; but my late examinations 
incline me to lean to their validity. Our figure well represents 
perfect specimens of the two. 
Plate 8. Woodsia Ilvensis, Br., fertile specimens,— nut. size. Fig. 1. Seg¬ 
ment of a pinna, with the scaly portion of the rachis, and with sori,— magni¬ 
fied. 2. Involucre and portion of a sorus ,—more magnified. 
