558 
Froceedings of the Royal Irish Academy. 
It must be mentioned here that tlie numbers given as heights 
represent an enormous number of observations. Every species was 
made a special study on each mountain ; and for fuller information 
the reader must refer to the various papers indicated on page 570. 
I will now draw attention briefly to some points of comparison 
between Irish and British vertical distribution. The most interesting 
species found on the Irish mountains are those which do not occur 
elsewhere in the British Isles. These are : — 
Arenaria ciUata, 1950 to 1200 feet on Ben Bulben, Sligo. 
Saxifraya yeum (including S. hirsuta) 2650 feet (Kerry and Cork) 
to sea-level. 
S. umhrosa, 3370 feet to sea-level (Kerry and Cork) ; 2600 to 
500 feet (Waterford) ; 2680 feet to sea-level (Galway) ; 
2000 feet (to 800 feet Poisoned Glen), (Donegal). 
Arbutus imedo, 520 feet to sea-level (Kerry). 
Daheocia polifolia, 1900 feet (Mayo and Galway), to sea-level. 
Pinyuieula grandiflora^ 2250 feet to sea-level (Kerry and Cork). 
Sea-level signifies one or two hundred feet to actual sea-level. 
It will be seen that we have no truly Alpine species which is not 
found in Great Britain. On the contrary, our total number is a very 
small proportion (not a third) of those found east of the Irish Sea. 
Of this group the, only interesting ones are a few which descend to 
a lower level in Ireland than they do even in Scotland. It is some- 
what surprising that this should occur even in a single case when we 
reflect upon the fact that Scotland (including the islands) extends six 
degrees north of Ireland, and therefore, as a natural result, what are 
mountain species with us become lowland ones long before we reach 
the north of Scotland. Thus in Skye, Alchemilla alpina is about the 
commonest plant in some places right down to the sea ; and close to 
the base of Ben Lawers we meet with Polygonum viviparum, Rulus 
chamcemorus^ and other Alpines, which either do not occur at all in 
Ireland (e.g. Vaccinium uliginosum)^ or else only at considerable eleva- 
tion. The poverty of Ireland in this respect is the more remarkable 
since the climate is well suited for many of these absentees, and their 
absence can only be accounted for by the simple geographical fact 
that they never reached us. 
