INTRODUCTORY EXPLANATIONS. 23 



The summit of Ben-muich-dhu certainly exceeds 4,000 

 feet above the sea, and is commonly estimated between 

 4,300 and 4,400 feet. Observations taken on this \mfavom-- 

 able day, with Adie's sympiesometer, gave 4,320 feet for the 

 base of the caiiia which marks the smnmit. While de- 

 scending rapidly from this cairn, all the observed phaeno- 

 gamic species were entered in a note-book, successively in 

 the order in which they first came under notice. The fol- 

 lowing series of names will therefore show the relative alti- 

 tude at which the several species appeared, and, of course, 

 indicate their upper limit in the the track of descent : — 



Juncus tiifidus. 



Vaccinium Myrtillus. 



Aira (alpina ?) 



Viola palustris. 



Empetrum nigrum. 



Alchemilla alpina. 



Carex panicea. 



Saxifraga stellaris. 



Sibbaldia procumbens. 



Rumex Acetosa. 



Caltha palustris. 



Vaccinium uliginosum. 



Aira flexuosa. 



Scirpus caespitosus. 



Eriophorum angustifolium . 



Epilobium alpinum. 



Rubus Chamaemorus. 



Arabis petraea. 



Cochlearia groenlandica (Aut. Brit.) 



Armaria maritima. 



Apargia Taraxaci. 



Luzula campestris. 



Galium saxatile. 



Anthoxanthum odoratum. 



Azalea procumbens. 



Calluna v'jlgaris (2,690 feet). 



