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XXIII. Remarks on some British Ferns. By Mr. David Don, Lihr. L.S. 



Read March 18th, 1834. 



JVl Y attention having been lately directed to the examination of some species 

 of Ferns more recently added to the British Flora, with a view to determine 

 how far they merited the rank which has been assigned to them, I beg leave 

 to lay the results of my investigation before the Linnean Society, being per- 

 suaded that any attempts to clear up the synonymy of our native plants will 

 meet with its approbation and encouragement. I shall commence with the 



ASPIDIUM DUMETORUM, 



a species first proposed by our late President in the 4th volume of the English 

 Flora. This is made up of two plants, the one from Cromford Moor being a 

 dwarf state of A. dilatatum, and the other from Ravelston Wood, near Edin- 

 burgh, having the segments of the frond abruptly truncate, and the habit, at 

 first sight, altogether peculiar; but an inspection of the original specimens 

 in the Smithian herbarium proves it to be nothing more than an accidental 

 variety of the same species, namely, Aspidium dilatatum, arising from dis- 

 ease, which is shown by the sudden termination of the costse, and by the 

 partial decay of the other segments. Specimens of the more ordinary state of 

 A. dilatatum gathered at the same time and from the same locality are similarly 

 affected, but in a less degree. The distinctions derived from the fructification 

 in the English Flora are altogether fallacious, and are partly dependent on the 

 age of the frond, and partly on that of the individual plant. It is clear, there- 

 fore, that the Aspidium dumetorum must be erased from the list of species. 

 The next species I shall have to notice is the 



Nephrodium rigidum. 



I formerly expressed a suspicion of the correctness of the plant published 

 vol. XVII. 3 I- 



