60 WAYSIDE AND WOODLAND FERNS. 



in three Scottish counties at considerable elevations. First 

 recorded by Mr. W. Wilson about eighty years ago on Ben 

 Lawers, Perthshire, it has frequently been found there since, 

 and other localities have been discovered for it in several glens 

 of the Breadalbane Mountains in the same county, as also in 

 the Clova Mountains of Forfarshire, and near Braemar, Aber- 

 deenshire. Neither England, Wales, nor Ireland can boast of 

 a station for it ; but on the Continent it occurs on most of the 

 mountain systems of Northern and Middle Europe ; and in 

 Kamchatka and the Rocky Mountains. (Plates 55, 65.) 



As in the other species of Cystopteris, the English name is 

 only a translation of montana, the specific Latin name. 



The Shield Ferns (Aspidiiim). 



The Shield Ferns are of a more robust and sturdy nature than 

 those we have been just considering, so much so that in most 

 of their natural haunts they retain one year's fronds until the 

 next year's growth is fully expanded. The principal character 

 of the genus is found in the indusium, which is circular and 

 attached to the frond by a central stalk on the underside 

 (Plate 4). In botanical language it would be said to be 

 " orbicular and peltate," both terms being well exemplified in the 

 familiar leaf and stalk of the Garden Nasturtium (Tropaolunt). 

 There are over fifty known species in the genus, of world-wide 

 distribution. The question whether there are two, three, or 

 four British species is one of the vexed points in botanical 

 classification and nomenclature, and much confusion exists in 

 books on Ferns respecting the name of the genus. In some 

 works it is correctly set down as Aspidium, in others as Poly- 

 stichum. The explanation which we make for the benefit of 

 fern-lovers who may be puzzled by this state of things is, that 

 the genus Aspidium of Swartz has been subdivided on secondary 

 points of resemblance. The British species belong to the 



