2 BRITISH FERNS. 



and other early systematic botanists resorted, in the first instance, 

 to the shape of the frond, than which nothing is more vague, 

 unnatural, or uncertain, as a generic distinction. Limieus and 

 his followers have trusted to the shape of the masses of capsules, 

 whether round, oblong, linear, or indeterminate, whence far 

 better characters are obtained, but not such as prove sufficient. 

 The writer of this, furnished with a vast collection of Ferns in 

 the Linnean Herbarium, and from that of Sir Joseph Banks, 

 first suggested an additional principle of arrangement, derived 

 from the form and insertion of the membranous cover or in- 

 wlucrum, and especially from the direction in which that part 

 bursts or separates from the frond when arrived at maturity ; 

 whether, if lateral, at the side towards the margin of the frond, 

 or of its segments, or towards the rib or vein ; or if terminal, 

 towards the extremity or contrariwise. This principle is found 

 to produce very certain distinctions, and to establish the most 

 natural genera. All subsequent writers on Ferns have adopted 

 it. English Flora, iv. 279. In a few short years we find this 

 favourite character almost lost sight of, and a fourth, that of the 

 venation, rapidly superseding it. 



Most authors have admitted the importance, for purposes of 

 nomenclature, of those characters which are spoken of by Smith 

 as derived from the fructification ; but, until lately, other 

 characters of equal value, drawn from the situation of the veins, 

 have been entirely neglected ; this is now no longer the case, and 

 I am inclined to believe, that henceforward, in the veins of a new 

 fern will be sought the characters which shall decide its genus. 

 At present, I can say but little for the correctness of our writers 

 on this subject. Presl has published an expensive and highly- 

 illustrated work, professing to exhibit the venation of every 

 genus ; but he has not paid the subject that close attention which 

 it requires : of the British species few are perfectly accurate ; 

 some, as Allosorus crispus, are either drawn from supposed 

 memory, or from imagination ; and many important and obvious 

 characters, as the anastomozing veins of Ceterach officinarum, he 

 has entirely overlooked. If the exotic species are drawn in an 

 equally careless manner, the work is of little value. 



Mr. Smith, of the Royal Botanic Garden at Kew, has paid 

 great attention to the venation of Ferns ; he has prepared an 

 essay on this subject, which I trust we shall shortly see in print, 

 and I am sure, from my knowledge of the way in which he has 



