ANNOTATIONS AND ADDITIONS. 159 



surrounding snowy covering, and which may possibly be 

 warmed by heat ascending through open fissures. I have 

 already spoken of the Saxifraga boussingaulti, which is found 

 on the Chimborazo at an elevation of 14800 (15773 E.) 

 feet ; in the Swiss Alps, Silene acaulis has been seen at a 

 height of 10680 (11380 E.) feet, being in the first-named 

 case 600 (640 E.) feet, and in the second 2460 (2620 E.) 

 feet above the limit of the snows, that limit being taken as 

 it was in the two cases respectively at the time when the 

 plants were found. 



In our European Coniferse, the Red and White Pine shew 

 great and remarkable differences in respect to their distri- 

 bution. While in the Swiss Alps the Red Pine (Pinus 

 picea, Du Roi, foliis compresso tetragonis; unfortunately 

 called by Linnaeus, and by most of the botanists of the 

 present day, Pinus abies !) forms the upper limit of arbo- 

 rescent vegetation at a mean height of 5520 (5883 English) 

 feet, only an occasional low growing mountain-alder (Alnus 

 viridis, Dec., Betula viridis, Yill.) advancing now and 

 then still nearer to the snow-line ; the White Pine (Pinus 

 abies, Du Roi, Pinus picea, Linn., foliis planis, pectinato- 

 distichis, emarginatis) ceases, according to Wahlenberg, more 

 than a thousand feet lower down. The Red Pine does not 

 appear at all in the South of Europe, in Spain, the Appen- 

 nines, and Greece ; even on the northern slope of the Pyre- 

 nees it is seen only, as Ramond remarks, at great elevations, 

 and is entirely wanting in the Caucasus. The Red Pine 

 advances in Scandinavia farther to the north than the 

 White Pine, of which last-named tree there is in Greece 



