7O WAYSIDE AND WOODLAND FERNS. 



but there are authorities who consider them as all sub-species 

 of one. Their point is that, though certain forms regarded as 

 species stand out so distinctly from each other as to warrant 

 specific rank when considered apart from intermediate forms, 

 yet that when the four so-called species and their varieties are 

 all regarded together we get a series whose forms merge into 

 each other, so that it is difficult to say where Nephrodinm 

 cristatum ends and N. spinulosum begins. The position is 

 not rendered more simple by the existence of Nephrodium 

 remotum, a sub-species of N. spinulosum which connects the 

 latter with the Male-fern. (Plates 71, 79.) 



The Crested Buckler-fern at first sight suggests affinity with 

 the Prickly Buckler-fern (N. spimilosuni), though the narrow- 

 ness of the fronds makes it sufficiently distinct to arrest the 

 attention of those whose walks lie in the few districts of this 

 country where it grows. It is a fern of boggy or marshy ground, 

 where the short scaly rootstock creeps just below the surface 

 and divides into several heads, each producing its tuft of a few 

 fronds. The fronds are from twelve to eighteen inches long, of 

 which length nearly one-third is contributed by the pale scaly 

 stipes. The scales, investing not only the stipes but the root- 

 stock also, are large, pale, and bubble-like. The leafy portion 

 of the frond is oblong lance-shaped, pale green and polished. 

 The pinnae, which are almost opposite, are reduced in length 

 very gradually upwards from the lowest pair but one, which are 

 slightly larger than the lowest. The largest pinnae are about 

 two inches long, of triangular form, and attached to the rachis 

 by short footstalks. The pinnules are oblong, deeply and 

 sharply toothed, and attached by the whole width of their base. 

 There are barren and fertile fronds, the former being broader 

 and softer. The fertile fronds bear on the pinnules two rows 

 of sori, near to the midrib. The indusium is quite smooth, 

 without glands or fringe ; and the spores are ripe in August. 



A peculiarity of this species is seen in the unrolling frond, 



