HEMESTHEUM THELYPTERIS. 125 



a genus of ferns is a perfectly arbitrary assemblage of species. 

 Schott was the first to propose a more restricted genus, under 

 the name of Thelypteris ; and I should unhesitatingly have 

 adopted it, had I not an insuperable objection to change a Lin- 

 nean specific name, a course that would be necessitated by the 

 transference of that name to a genus. This fern is an admira- 

 ble example of the present state of fern-classification : nothing 

 could possibly exhibit more clearly its chaotic state. 



This species occurs in every country in Europe, and in Asia- 

 tic Eussia : it is said by Sadler to occur also in North Africa, 

 and in North and South America ; North America I can con- 

 firm, being indebted to Mr. Boott for both fronds and living 

 plants from the United States, which are so similar to our Bri- 

 tish plant that I am unable to detect any character by which to 

 distinguish them. 



In this country it must be considered local, but its distri- 

 bution is very general. It occurs only on those boggy heaths 

 where the soil is so moist and light that its rhizome can ex- 

 tend itself with rapidity and freedom : in such situations it is 

 found in great abundance. The list of localities which I have 

 received through the kindness of correspondents, is far too 

 voluminous to publish; I shall therefore only give a general 

 summary, from which it will be observed that as regards the 

 English and Welch counties, it occupies tracts that are avoided 

 by the ferns of mountainous regions. 



In Scotland it is a fern of excessive rarity : some of the few localities 

 which have reached me have turned out on investigation to have originated 

 in an error, a small frond of Lastrea montana having been mistaken for 

 the present plant. Through the kindness of Scotch botanists, I have re- 

 ceived very careful lists of the ferns of Argyleshire, Dumbartonshire, Dum- 

 friesshire, Kirkcudbrightshire, Lanarkshire and Renfrewshire, and from all 

 of these it is absent. I am indebted to Mr. Watson for the information of 

 its occurrence ia Forfarshire, on the authority of Mr. R. Maughan ; Mr. 

 Watson adds, " not in fruit, but I believe the name correct." Again, in 

 ' Cybele Britannica' (iii. 365), he speaks of having a specimen from Mr. 

 Maughan in his own herbarium. 



