1061 



allied, they may be readily distinguished from each other ; and that 

 at the present day they are considered as distinct species, by general 

 consent, in Sweden, although formerly united.* On the other hand, 

 there appears to be a want of positive characters, from which a good 

 specific diagnosis might be framed ; the differences between them 

 being principally in degree, which is probably the cause of E. fluvia- 

 tile having been overlooked in Britain so long. For this reason, spe- 

 cimens somewhat intermediate may occasionally be noticed; — luxu- 

 riant states of the barren stems of E. limosum, in which the whorls of 

 branches have become more divaricated than usual, and spring from 

 slightly coloured sheaths, much resembling diminished forms of E. 

 fluviatile, when seen singly in a dried state. But, so far as I can 

 judge, when they are fully examined in their native localities, or a 

 .sufficient series of characteristic specimens studied when dried, there 

 need not be any difficulty in distinguishing one from the other. But 

 whether the distinctions are sufficiently decisive and permanent in 

 character to separate them as species, must be left for time and more 

 extended observation to determine. f 



With regard to the Linnean nomenclature, three alternatives pre- 

 sent themselves for our consideration : — 



1. That Linneus applied the names "limosum" and " fluviatile " 

 to the plants described under the same names by Fries. 



'2. That he was unacquainted with E. fluviatile, Fr., and applied 

 the two names to the branched and unbranched forms of E. limo- 

 sum, Fr. 



3. That he was acquainted with both of the supposed species, but 

 united them together ; in the ' Systema Vegetabilium ' applying the 

 name " limosum " to the almost branchless form, the " Equisetum 

 nudum la^vius nostras " of Ray ; and that of " fluviatile " to the more 

 compound variety ; but afterwards, finding they were not specifically 

 distinct, omitted the former from the ' Flora Lapponica.' 



Of these propositions, the first is decidedly incorrect ; because the 



* " E. limosum et E. fluviatile utique nimis afSnia sunt, sed apud nos (circa 

 Upsaliam vulgaria) facile discernuntur et a nullo Botanicorum Suecorum, ad prisca 

 contrahenda quara nova distinguenda promptiorum, conjuncta." — Sum. Veg. Scand. 

 p. 251. 



t My large supply of specimens of E. fluviatile, and of the variety of E. limosum 

 with furrowed ribs, will principally be distributed through the medium of the London 

 Botanical Society. J would respectfully recommend this point to the notice of those 

 who may receive them, 



VOL. IV. 6 u 



