12 MB. J. BALL ON THE FLOEA 



being common to both. In the Amsmiz valley tlie conditions 

 were more nearly similar, and afford better ground for comparison. 

 In that yalley we collected 225 species, 162 being found in the 

 middle and 91 in the superior zone, 2S species being common to 

 both zones. The opportunities for collecting in the middle zone 

 were less than at Chicla^ but much more favourable in the superior, 

 as we were able to examine the ground rather closely in the 

 course of an ascent and descent through a vertical height of 



^.X C* .V..U.V.CVX ..^.^ 



more than 4000 feet. My general conclusion is that, as regards 

 variety of vegetation, the western and most sterile slope of the 

 Peruvian Andes is at least as rich as the northern slopes of the 

 Great Atlas, and probably far superior to the southern slopes of 



that range*. 



In considering the bearing of the facts here brought together 

 on questions connected with the past history and origin of the 



* Since the above lines were written I have had opportunities for comparing 

 the results obtained in the Andes with those procurable under similar con- 

 ditions in the Swiss Alps. During three days, between the 12th and 15th 

 August, I noted all the species seen in flower or fruit abore the Baths of 

 Eosenlaui in the Bernese Oberland, between the levels of 4500 and 5200 feet 

 above the sea, corresponding as well as I could estimate with the range of my 

 fibort excursions from the village of Chicla, On the 2nd of August, I noted in 

 the same manner the species observed in two separate areas above the summit 



8000 



west 



the other nearly due north. In both the latter observations, while devoting 

 about the same time that I was able to give in the Andes above Casapalta, I 

 covered more ground, with the result of obtaining many additional species. 

 The reason for omitting from my Alpine lists plants not seen either in flower 

 or fruit is, that in the Andes I abstained from collecting plants which I should 



be unable to determine- 



My Rosenlaui list includes 143 phanerogams and 7 ferns against 129 phanero- 

 gams and 7 ferns collected about Chicla ; and it is worthy of note that in each 

 list nearly three fourths of the phanerogams belong to the same natural orders. 

 In the Furca lists the better exposed area afforded me 65 species, and the less 

 favourably situated slope only 45 species, 30 species being common to both. 

 Bearing in mind the fact that a larger area was in both cases examined, I came 

 to the conclusion that, as regards the true alpine zone, the portion of the Andes 

 seen by me supports a vegetation as varied as that of Central Switzerland ; while 

 as regards the subalpine region, the Alps display a somewhat more varied vege- 

 tation. The range of individual species appears to be decidedly greater in the 

 Alps than iu the Andes, as is shown by the fact that out of 80 species seen 

 abjve the Furca Pass, growing on crystalline schists near the superior limit of 

 vegetation, 18 species were found in the valley of Eosenlaui at a level lower 

 by 2500 or 3000 feet, and growing on calcareous soil. 



I have no doubt that on the southern side of the main chain the Alps usually 

 exhibit a much more diversified vegetation. 



