542 TRANS. OF TIIE ACAD. OF SCIENCE. 



JUNCACE/E. 



* Luzu'.a spicata, DC. Eu. As. 

 L. parviflora, DC. Eu. As. 

 Juncus Drumondii, Meyer. 



* Juncus Hallii, Engel. 



* J. Parryi, Engel. 



* Juncus triglumis, L. Eu. As. 



* J. castaneus, Stu. Eu. As. 



CYPERACE.E. 



Carex atrata, L. Eu. As. 

 C. rigida, Good. 



* C. incurva, Lightf. Eu. 



* C. filii'olia, Nutt. 



GHAJ1INO. 



Phleum alpinum, L. Eu. As. 



* Poa Andina, Nutt. 



P. alpina, L. Eu. As. 



* P. arctica, R. Br. 



P. nemoralis, L. Eu. As. 



Aira casspitosa, L., var. arctica, Thurb. Eu. 



Festuca rubra, L. Eu. As. 



F. ovina, L. Eu. As. 



Triticuui strigosum, Less. As. 



FILtCES. 



Cryptogramme acrosticboides, R. Br. 



SUMMARY. 



As a brief recapitulation of the main points here presented, 

 I offer the following condensed summary: 



1. The persistent bodies of snow which, in variable amount 

 at different seasons, are ordinarily met with on the higher 

 elevations of the Rocky Mountains, do not indicate a region 

 above the true snow line, but result from the accumulation of 

 drifted snow, filling up recesses and sheltered depressions to 

 such an extent that the summer sun is not sufficient to mell 

 the deeper portions, which thus remain from year to year, 

 varying in amount according to the quantity of fallen snow, 

 or the character of the succeeding summer season as to its 

 snow-melting power. 



2. Hence, we have no constant accumulation of snow, form- 

 ing what is known in the European Alps as Nhve, the pressure 

 of which from the higher elevations gives origin to glaciers. 



3. In the absence of glaciers and heavy snow accumulations 

 on mountain slopes, Ave do not encounter the usual glacier 

 phenomena so often referred to in the European Alps, and 

 only meet occasionally with avalanches due to accidental local 

 causes. 



4. 1 he winter snows being of the light character pertaining 

 to the higher regions of the atmosphere, and not subject to 

 condensation by alternate thawing and freezing during the 

 season of their occurrence, are thus peculiarly liable to the 



