218 
[March, 
Pontresina itself lies at an elevation of 5915 feet, and the district 
explored by me occupies about ten miles in various directions there- 
from, and at from 5600 ft. to 6800 ft. in elevation. The return 
journey was via the Julier and Schyn Passes (arrangements having 
been made, in the meantime, for the conveyance of passengers and 
their belongings on an improvised raft across the river at Reichenau), 
and the highest point at which any Trichopterous captures were made 
was the little inn on the summit of the Julier Pass (7503 feet) 
during the short time the diligence stopped. 
The principal hunting-grounds were the Yal Roscg as far as the 
glacier ; the Lake St. Moritz, and the Statzer-See (in the wood) 
which discharges into it ; the Yal da Fain (no doubt a paradise for a 
Lepidopterist, but practically useless for my purposes, owing to the 
utter absence of trees and the snow-fed stream) ; the wild rocky 
ground in a forest of larch and arolla ( Finns cembra ) through which 
the torrent from the Piz Languard finds its way ; a nearly similar 
locality on the right of the road to Samaden ; the Yal Celerina (in 
w r hich are magnificent old larches) ; and the Yal Bevers. 
In my “ Revision and Synopsis of the Trichoptera of the European 
Fauna,” Appendix, p. xciv, I pointed out the deterrent effects of the 
vicinity of glaciers on aquatic insect-life. Those remarks came before 
me very vividly on this excursion. The stream at Pontresina, termed 
the Flatzbach, is utterly devoid of Trichopterous life, being poisoned 
by the Roseg and Morteratsch glaciers, but above the latter it is pro- 
ductive. A glacier-fed stream is turbid and milky ; a snow-fed stream 
is usually clear and blue after the spring and early summer meltings 
are over, but even such a stream as this is seldom very productive, 
unless it is also largely fed by lateral rivulets from land springs, and 
these latter arc the best of all. Naturally, in such a district these are 
not abundant, and long distances must he travelled over for their 
discovery * 
The results of my excursion were about 450 specimens, repre- 
sented by the species enumerated below. Rather to my disappoint- 
ment, no species that can absolutely be identified as new was dis- 
covered ; but some purely alpine forms were abundant ; still, however, 
not so great a number of species were taken as I had anticipated 
finding. There was a marked absence of those small forms usually 
so abundant in lower districts where the water is warmer. The 
* Geological conditions also infl tnee aquatic insect-life. Limestone districts are probably 
the best. Schist is fatal : perhaps the most remarkable instance of this is to be seen at Thusis, 
where, in consequence of schist, the l^olla, at its junction with the Rhine, is of inky blackness, 
and useless for entomological purposes. 
