1 68 ANNALS OF SCOTTISH NATURAL HISTORY 



the Atholl district also, the aspen does not get higher than 

 640 m., though the tree is common in the Highlands. 



As compared with Scotland, alpine plants descend to 

 lower levels in Ireland. So, as a matter of contrast in the 

 following List as regards altitudinal range, the descending 

 level reached by those Scottish alpine plants which occur in 

 Ireland is given, and is taken from the second edition of 

 " Cybele Hibernica." In the matter of bibliography, the five 

 works subjoined are frequently cited, and to save space in 

 reference are quoted in the abbreviated form appended to 

 their titles : 



H. C. Watson, "Cybele Britannica," vols. i-iv (1847-59) " Cyb. 

 Brit." 



N. Colgan and R. W. Scully, "Cybele Hibernica," ed. 2 (1898). 

 "Cyb. Hib." 



G. Dickie, " Botanist's Guide to the Counties of Aberdeen, 

 Banff, and Kincardine" (1860). Dickie. 



"Scottish Naturalist," continued (after 1890) as "Annals of Scot- 

 tish Natural History"(i 87 1-1908). "Ann. Scot. Nat. Hist." 



F. B. White, " Flora of Perthshire " (edited by Prof. J. W. H. 

 Trail, 1898). "Fl. Perthsh." 



Among British county-floras Dr. White's work occupies 

 an unique position, not only in many features associated with 

 its compilation which are far in advance of previous local 

 floras, but in the admirable series of observations of the 

 altitudinal range of plants made personally by means of the 

 aneroid barometer, which considerably enhance the value of 

 the work as a contribution to British Geographical Botany. 

 It is this feature of the flora which not only suggested the 

 preparation of the present paper, but supplied data for com- 

 paring the details of altitudinal range of plants in other 

 Highland counties, and has provided the basis for the present 

 contribution to the subject. Watson's altitudes must be 

 accepted with some misgiving, and only where more recent 

 observations are not available. Many of those which he 

 vouched for personally were made more than seventy years 

 ago, before Vidie's invention of the aneroid barometer ; and 

 the information which he received second-hand was frequently 

 from unreliable sources. Watson used an old-fashioned 



