7 



tus, often of great depth, resulting from the disintegration of 

 these fragments by glacial action and atmospheric influences, the 

 latter of which, at this elevation, possess a strength and power 

 unknown in lower tracts. Amongst these stones and this detritus 

 large patches of unmelted snow in the hollows greet the eye, 

 even in the warmest summers, from the lower margin of which 

 there usually issue forth the cold waters of springs and rills. 

 Upon the whole summit but a very scanty vegetation is seen, 

 consisting chiefly of mosses and sedges, though all the different 

 classes of our flora have their representatives. With the names 

 of these I need not at present trouble you, but shall simply state 

 that of phsenogamic plants there occur only some seven species, 

 the test plant of this alt-alpine zone being luzula arcuata, which 

 descends only some 700 feet. The cryptogamics, however, are more 

 plentiful and varied, the test plants of this zone in the different 

 families being lycopodiurn selago f. minor for the Filicince, 

 andreoea nivalis for the Musci, iungermannia orcadensis for the 

 Hepaticse, lecidea arctica for the Lichens, protococcus nivalis for 

 the Algae, and agaricus nivalis for the Fungi. All the alt-alpine 

 plants bear a strong resemblance to those of more northern lati- 

 tudes in their social and stunted manner of growth, in the rela- 

 tive proportion of phamogamics to cryptogamics, as also of the 

 different tribes of these to one another. But leaving this zone, 

 we arrive, after a gradual descent of about 850 feet from the 

 summit, at the mid-alpine zone, which presents very distinct and 

 well-marked features from the one above. Like the preceding, it 

 is very well and completely defined on Ben-na Machdui on every 

 side, save the two already mentioned. It consists chiefly of lofty 

 and nearly perpendicular precipices, sometimes 1,500 feet in 

 height, usually of a more or less semicircular form, so as to con- 

 stitute, as it were, a large deep hollow in the sides of the mountain, 

 whence the Gaelic name corrie, literally a caldron, applied to such 

 places. The rocks of these precipices are occasionally solid and 



