208 THE BRITISH FERNS. 
Asiatic Russia, and from Siberia. The variety pallida, which is 
scarcely different, is found in the south of Europe where it spreads 
from Italy and Spain, to Greece, as well as in Northern Africa. 
The Aspidium argutum of Kaulfuss, from California, is merely 
another variety, larger and more developed. The Dryoptera rigida 
of Dr. Asa Gray, found, though rarely, in Massachusetts, North 
America, which acquires a larger size and more developed character 
than the European rigida, proves to belong to the spinulosa type. 
The culture of this Fern is very similar to that of the other 
larger growing kinds, except that it is more impatient of moisture, 
and doubtless prefers a purer atmosphere. It grows well in free 
well-drained loamy soil; and the fact of its range being almost if 
not quite confined to limestone mountains, suggests that the use 
of limestone among the soil may be beneficial, though it is certainly 
not essential to success. It is of far more importance that the soil 
should be kept moderately moist, and should be of such a texture, 
as may at the same time prevent any accumulation of stagnant 
water. It is increased by separating the lateral crowns formed by 
the caudex. The latter is the better for being somewhat elevated 
above the soil in planting, for being decumbent in habit, it does not 
when planted deeply, liberate its crown so readily as the more erect- 
habited species. 
Mr. Wollaston has noticed a variation in which the fronds or the 
pinnao, or both, are simply or multifidly divided at the apex; and 
Messrs. Stansfield and Son, of Todmorden, have a small ramose 
form, obtained from Ingleton Fells, but neither of these prove 
to be constant forms. 

