xiv PEEFACE TO THE EIEST EDITIOIST. 



And, as some additional species may be tereafter found in Ireland, 

 ■we belioTe that tte use of some book containing descriptions of tbe 

 entire series of British, plants will be found advantageous. 



Our scope being thus limited, we have endeavoured to include, in 

 a compendious form, as much information respecting the localities 

 and range of Irish plants as can be given within a short compass. 

 On account of the fewness of the observations hitherto made on the 

 upper and lower limits of the elevation of plants, we have preferi'ed 

 to reserve the complete details of this part of our subject for a 

 future edition. And here we would especially recommend this 

 interesting branch of study to those of our botanists who are in the 

 habit of spending a part of the summer in a mountainous district. 

 A rough estimate of the upper and lower Kmits may be made from 

 the Ordnance Survey map, on which the heights are carefully laid 

 down, but it is especially desired that careful observations of both 

 upper and lower limits be taten with the barometer (or sympieso- 

 meter) in each of our mountain districts separately, since this is the 

 only way to secure data for a just estimate of the influence of 

 climate on the upper and lower limits of plants, as the "zones " 

 and "regions" in Donegal must range to very diEEerent heights 

 from those in Eerry or the East of Ireland. "We believe that little 

 is gained by the statement that a species descends to sea-level in one 

 district, while it ascends to 3000 feet in another \ it is only by- 

 comparing both upper and lower limits in each different range of 

 hUls, or at least in each of the chief groups that any useful results 

 can be expected. The elevation of many species is carefully noted 

 in the MS. catalogue of the Plora of the county of Londonderry, 

 drawn up under the directions of the officers of the former Ordnance 

 Survey of Ireland; and Dr. Dickie's ''Flora of Ulster" is another 

 source from which we have frequently drawn— we can only regret 

 that more details were not given by so accurate and careful an 

 observer. 



Eor the localities, we have endeavoured to lay the foundations 

 altogether afresh upon recent and reUable authority, having 

 received from numerous correspondents, some twenty tolerably 

 complete county lists. "With these we have incorporated most of 



