THE BUCKLER FERNS. 65 



in this variation, and it has been pointed out that whilst lobatum 

 is chiefly found in Scotland and the North of England, where it 

 is the prevailing form, in the Midlands its place is largely taken 

 by aculeatum, which gradually merges into angulare as we 

 come farther south, the latter form not appearing north of the 

 Clyde. 



One or the other of these three forms (or their intermediates) 

 may be found in suitable places anywhere between the extreme 

 north and south of these islands, from Orkney to Jersey and 

 including Ireland. Their further distribution includes Europe, 

 Northern and Western Asia, the Himalaya, and North America. 



The English names are all book-names. It is probable that 

 our forefathers would not distinguish this from the Male-fern, 

 and the generic Fern or Farn would be applied, as it still is in the 

 country, to cover most of the species that have no strikingly 

 conspicuous appearance that suggests a distinctive name. In 

 Cornwall, however, we met with Lace-fern as a name for 

 A . angulare, and think it may be a genuine folk-name, for it is 

 very expressive of the natural appearance of the soft fronds. 

 The scientific names are so closely related to words adopted in 

 everyday speech that it is scarcely necessary to explain them. 

 Aculeatum is the Latin for prickly ; lobatum from lobus, a lobe ; 

 and angulare the Latin form of angular. 



The Buckler Ferns (NepJirodium). 



The distinguishing feature upon which the genus Nephrodium 

 is separated from Aspidium is again the form of the indusium, 

 which here takes the conventional kidney-shape, the attachment 

 to the vein of the pinnule being at the notch in the margin of 

 the indusium (Plate 17). There are seven British species, of 

 which some authors make nine. This is a case in which all the 

 Continental species of the genus occur in this country. The 

 genus as a whole is a very large one, and it has been split up 



