172 IX. ASPLKSICM 
therefore, appear either simply slit away from the main 
division, or they are so deeply divided and narrowed 
downwards as to assume the appearance of distinct pinna-. 
The veins are nearly simple, that which extends into 
each division of the frond proceeding directly from the 
base, and becoming forked upwards when the lobes are 
furnished with bifid teeth, one branch then extending to 
each tooth ; most of these venules bear a sorus on the 
inner side. The central lobe of the frond has usually one 
venule paralled with, and near to each margin, and each 
of these venules bears a long narrow sorus attached to the 
inner side, the indusium opening by its inner edge. The 
opposite position of these veins, and proximity of the sori, 
which open face to face, produce some resemblance to the 
twin fructification of Scolopendrium ; but the true nature 
of the son is sufficiently evident in the earlier stages of 
development, when they are seen to be perfectly distinct, 
each having its own indusium. Each sorus is covered by 
a linear membranous indusium, the free margin of which 
is entire ; this is pushed back by the spore-cases and finally 
lost, the sori becoming confluent and the entire surface 
covered by the spore-cases. The fronds are persistent 
through the winter, the young ones appearing about 
April. The fructification is mature in August 
This is a rare species, confined to the counties of 
Somerset, Carnarvon, Denbigh, York, Northumberland, 
Cumberland, Westmoreland, Roxburgh, Edinburgh, and 
Perth, and apparently not found at all in Ireland. It is 
however, not unfrequent throughout Europe, most com- 
mon in the south, and is found in the mountains of Asia. 
This and the preceding minute species require shelter, 
and constant but moderate and not stagnant moisture. In 
the climate of London they grow well in pots, in cold 
close frames, but do not bear exposure. The present spe- 
cies is somewhat tender, the young growth being liable to 
suffer from spring frosts. 
