ON THE BOTANICAL SUBDIVISION OF IRELAND. 63 



average area of these portions being 818 square miles. This size is 

 almost identical with tlie average size of Watson's 112 vice- 

 counties of Great Britain, which is 804 square miles. 



Next, as to the order in which the counties and vice-counties 

 should be numbered. . Watson numbered the British provinces I. 

 to XVIII., commencing with S.W. England and ending with the 

 extreme north of Scotland. The vice-counties he numbered in the 

 same order, those included in Province I. being numbered 1 to 6 ; 

 those of Province II. 7 to 14, and so on. Babington proposed a 

 similar method for Ireland, but the result is not satisfactory. The 

 Irisli " provinces " are not numbered regularly from south to north, 

 but the numbering runs first up the east coast, and then drops 

 back into the south-west ; and this absence of regular progression 

 becomes accentuated if the vic-3-counties are numbered in the 

 sequence of the provinces ; when, for instance, we suddenly pass 

 from Louth (127) 120 miles south-westward to Limerick (128). It 

 will be generally admitted that the best scheme, and the most 

 natural, is one which will show a regular progression from south to 

 north — from a higher temperature to a lower : with such a system, 

 the largeness or smallness of the numbers in the list showing the 

 county-distribution of a species, will themselves.be a key to the 

 northward or southward range of the plant. Thus, if out of, say 

 forty vice counties, we find the range of a plant is from 1 to 20, we 

 will immediately know that it is confined to the southern half of 

 Ireland. It appears to me that the practical advantages of such a 

 plan are much greater than those which arise from a consecutive 

 numbering for the vice-counties of each "province"; and the 

 scheme which I suggest therefore embodies this principle. A glance 

 at the botanical map in Ctjhcle Hibernica shows that the charac- 

 teristic plants of Ireland are distributed according to lines which 

 have a general trend north-west and south-east, rather than west 

 and east ; this is also the course followed by the isothermal lines of 

 winter and spring ; and I have adopted a system of numbering that 

 follows these natural lines, and proceeds in a regular manner from 

 the extreme south-west of the country to the extreme north-east. 

 Such a plan does not prevent the vice-counties being grouped under 

 the " provinces " if for any reason this is desired. We would then 

 have the followmg table ; for the " provinces " I give the numbers 

 used by Moore and More in Cyhele Hibeniica : — 



[ 1. South Kerry. 



1. South Atlantic . . . . i 2. North Kerry. 



( 3. West Cork. 



' 4. Mid Cork. 



5. East Cork. 



6. Waterford. 



7. South Tipperary. 

 11. Kilkenny. 



3. Babrow \1S. Carlow. 



2. Blackw^ater 



4. Leinster Coast . . 



14. Queen's County. 

 12. Wexford. 

 20. Wicklow. 



