57 



berland ; in three or four places about Borrowdale, Cumberland, 

 growing in the clefts of the rocks ; and Mr. W. Hawker writes that 

 he met with two plants of it this summer (1854) growing with 

 Asplenium septentrionale, on a precipice near Scaw-fell. In North 

 Wales, it has been collected near Llanrwst, and in the Pass of 

 Llanberis. The habit of this fern approaches so nearly that of the 

 preceding, that many botanists consider them to be merely varieties 

 of the same species ; and some forms of A. Ruta-muraria certainly 

 do resemble it in foliation, to a degree that appears at first sight 

 to render the question of identity far from doubtful : the general 

 outline of the frond, however, and its division are very different ; 

 in the present it is narrow lanceolate or linear, and never more than 

 simply pinnate, it is likewise of thinner texture and lighter green 

 colour. The pinnae, though varying in form and size upon the 

 same frond, are always distant and directed upwards; they are 

 generally of a narrow wedge-shape rapidly attenuated downwards 

 into a slender stalk, toothed or notched at the extremity, and, the 

 lower ones especially, not unfrequently divided into two or three 

 lobes ; not however showing any tendency to the bipinnate charac- 

 ter. The sori are developed like those of its near ally, but differ 

 in the margin of the indusium being entire. The fronds are usually 

 from two to four inches in height, but some preserved specimens 

 from the Tyrolese mountains measure six or seven inches. 



The scarcity of this fern has hitherto prevented experiment upon 

 its growth in the open air, in which it would probably succeed as 

 well as the preceding. It is usually kept in the house covered by 

 a bell glass, but is liable to die off during winter, and even in the 

 full growth of summer, without frequent attention to change of 

 air, and avoiding the accumulation of moisture upon the fronds. 

 In planting it is advisable to keep the crown a little elevated above 

 the surface, and the soil may be a mixture of sand and peat, to 

 which some add a little decayed vegetable mould ; I do not con- 

 sider the latter necessary, if it be not injurious, by contributing to 

 the retention of water around the roots, the supply of which ought 

 to be limited so as merely to prevent positive drought. 



It is remarkable that the plant before us should occur both in 

 this country and on the Continent in company with Asplenium 

 septentrionale, and always very sparingly. To even hint at any 

 probability of connection between them will perhaps horrify some 

 of our modern manufacturers of new species, accustomed as they 

 are to measure differences by half hair -breadths, but under the 

 risk of being classed as an innovator against all the established 

 laws of specific distinction among ferns, I believe this may be the 

 case ; indeed, that if the three British species of the Amesium series 

 are not really varieties of the same, dependent upon circumstances 

 influencing their primary development, the affinity of the present 



