19 
who had discovered it, and who had for many years devoted the most 
assiduous attention to studying the Equiseta and ferns of Ireland. 
This was the third striking form of unbranched Equisetum which had 
been discovered in Ireland; and all of these had now received a name 
at his (the President’s) hands: E. Mackaii, E. Wilsoni, and E. Moorei. 
He had once ventured on expressing an opinion that all the unbranched 
Equiseta were referrible to a single species ; and he found that conti- 
nental botanists were much inclined to adopt this view: but the ques- 
tion{must eventually be decided, not by the dictum of any man, but 
by carefully ascertaining whether the characters supposed to distin- 
guish them were constant or exceptional. Jf constant, it mattered 
httle how apparently insignificant ; and if inconstant and excep- 
tional, it mattered not how striking. ‘This principle was sound ; 
it could never be antagonistic to Nature’s laws. In the present 
instance, we had a plant apparently intermediate between hyemale 
and Mackaii, but differing in the possession of certain structural cha- 
racters peculiar to itself. Now, this difference, seeing that the plant 
had hitherto been discovered in only one station (although not in very 
limited quantities), might be attributed to the effects of season, aspect, 
or soil; but then, the stems of the older species, hyemale and Mac- 
kali, were persistent, while those of the new species were completely 
deciduous; and Mr. Moore found this difference to obtain equally 
when the plants were cultivated together, and the same conditions 
observed with all. He concluded by proposing the following charac- 
ters, as sufficient to distinguish the new plant from those with which 
we were previously acquainted ; and begged to express a hope that 
Irish botanists would endeavour, by diligent search, to extend the 
ascertained range of this interesting and strikingly beautiful species. 
EiquisETUM Moorsi, Newman. 
Rhizome not noticed. 
Stems annual, completely deciduous, 20—80 inches in length, 3 or 
4 united at base, perfectly erect, always unbranched, acuminate, 
gradually tapering throughout their length, with 12 (more or 
less) deep, well-marked striz; the surface rough and hard to 
the touch; divided by transverse septa into 12 (more or less) 
internodes, the middle ones of which are longer than those of 
either extremity. 
Sheaths loose, striated like the stem the interspaces between the 
striz having a deep central sulcus, of a beautiful pearly white, 
with a black ring at the base, and black tips to the teeth ; the 
