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We find that the Plinlimmon region is in this respeet similar to 

 the High Peak region, but dissimilar to the Lake region and the 

 East Highlands. The higher and more mountainous the country 

 is, the higher is the limit of any species ; in other words, within 

 certain limits plants are influenced by the proximity of the summit 

 of a mountain, and prevented from approaching it. Further in- 

 stances may easily be added to those above. Using Baker's test of 

 the Fruticose Rubi (exclusive of R. fissus) to determine the top 

 limit of the mid-agrarian zone, we find it to end about 750 to 

 850 ft. This is again lower than Watson's limit in the East 

 Highlands. 



The flora has an individuality of its own, — not altogether 

 unexpected, — apart from the prevalence of peat bog plants, e.g., 

 '■;■■'■>, i , 



Juncus squarrosus, Eriophorum, &c. This individuality shows itself 

 in the absence of Papaver* Ballota nigra, Petasites vulgaris, Lamium 

 nUnou, and Inula <lgs, ntoi<a : in i . •< nmm Leu- 



citnt/u mum, Brmnits, Malva rotundifolia, and Lemna; in the numerical 

 preponderance of plants of Cerastium glomeratum over C. trivial . and 

 of Muller'st shade form of Euphrasia officinalis over the larger form ; 

 and in the abundance of Chrysanthemum segetum. 



In calculating altitudes we have made as much use as possible 

 of the last Ordnance Survey Maps, and have thereby checked the 

 readings of our aneroid barometer. In conclusion, we desire to 

 thank Professor Babington and Mr. H. Groves for several kind 

 suggestions, and also the former for the use of his valuable 



PRIMARY SUBDIVISIONS IN THE GENUS SILENE. 

 By F. N. Williams, F.L.S. 



It is a quarter of a century since Paul Rohrbach, whose early 

 death from consumption cut short a promising career and was a 

 great loss to science, enriched systematic botany with an elaborate 

 analysis of the genus 8ilene.\ For doggedly pursued research of 

 essentially Teutonic brand, and capacity for laborious discrimi- 

 nation, it compares with Engler's monograph of Saxifraga and 

 IJ.-iu.-^kuecht's monograph of Epilubium. 



Since 1808 a large number of new species have been described 

 (especially from Eastern countries), and much material for the 

 elucidation of previously described species has been accumulated 

 and in part examined : the re-adjustment of groups of species has 

 proceeded with the examination of new material : the affinities of 



studii d : and in a matter subsidiary to these, in the direction of 

 precision and uniformity, conflicting schools of nomenclature have 



