30 
EQUISETACE^. 
probation of my views ; and I think it well, in a worli like the 
present, to content myself with endeavouring to discriminate 
between the plants described, without making any other at- 
tempt to enforce my views as to the limits of species or varieties, 
than by recording the doubt which I feel on the subject by pre- 
fixing a t to the names of all those species whose distinctness I 
do not at present consider to be clearly proved. 
The stem cut transversely presents a section somewhat dif- 
ferent from that of E. hyemale : the furrow^s are wider, and 
the rows of siliceous particles rather more distant, yet less so 
than in E. variegatum. Magnified sections of all three are 
given in the vignette below : the central figure represents E. 
hyemale^ the right hand figure E. variegatum y and the left hand 
E. Mackaii. The sections were cut from specimens of average 
size, were magnified by the same power, and the outline traced 
by means of a camera lucida, so that the relative sizes of the 
three, as well as their proportions, are accurately preserved. 
Closely allied to the present species, but still to all appearance 
distinct, is the Equisetum ramosum of Schkuhr — the E. multi- 
forme ramosum of Vaucher and Decandolle. It is said by 
Schkuhr to have been found in Wales, but I do not know on 
what authority: it is figured and fully described both by Schkuhr 
and Vaucher, and specimens may be consulted in the herbarium 
of the late Mr. Winch, now in possession of the Linnean Soci- 
ety of London. 
