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HISTORY OF BRITISH FERNS. 
of differences of another kind, less obvious, perhaps, at 
the first glance, but doubtless of sufficient importance for 
the separation of species. This book being intended for 
the use of those who are only likely — at least whilst they 
require its aid — to study the smaller group, we shall point 
out the minuter differences which serve to separate the 
series of Crested Ferns into several recognizable forms. 
Lastrea cristata grows with very erect, narrow, oblong 
fronds, whose deltoid pinnm are not quite divided down to 
the central rib, and the lobes into which they are separated 
are attached by the whole width of their base, and are 
oblong, with a rounded apex. The stipes is sparingly 
furnished with broad, obtuse, membranous, whole-coloured 
scales, and the caudex is creeping. 
Lastrea uliginosa has two or three sorts of fronds ; one 
set, the barren earlier ones, has much resemblance to those 
of the preceding, the other sets producing fructification, 
being bipinnate at the bases of the pinnae, the fronds 
narrow-oblong, the lobes tapering to a point ; the scales 
of the stipes are broad, blunt, and whole-coloured ; and 
the caudex is creeping. This connects cristata with 
spinulosa. 
Lastrea spinulosa grows erect; has narrow, lance-shaped, 
