118 HISTORY OF BRITISH FERNS. 



marks of distinction. As this book is intended for the use 

 of those who are only likely at least whilst they require its 

 aid to study the smaller group, we shall endeavour to show 

 them how to understand the minuter differences which serve 

 to separate this series of Crested Perns into several recog- 

 nizable species ; and for this purpose shall first enumerate 

 the leading features of distinction : 



Lastrea cristata grows with very erect, narrow, oblong 

 fronds, whose deltoid pinnae 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. 



Lastrea uligmosa has two or three sorts of fronds ; one 

 set, the earlier ones, having much resemblance to those of 

 the preceding, the other sets producing fructification, being 

 bipinnate at the bases of the pinnee, the fronds narrow- 

 oblong, the lobes tapering to a point, and the scales of the 

 stipes broad, blunt, and whole-coloured. This connects 

 cristata with spinulosa. 



Lastrea spmulosa grows erect, has narrow, lance-shaped, 

 bipinnate fronds, and whole-coloured blunt scales to the 

 stipes. It is broader and more divided than the foregoing. 



