Niles.] 318 [April 2, 
ceeded in raising the imago, but no imago of this genus has 
been found in Europe. Westwood possesses specimens of 
Prosopistoma received from Latreille. | 
April 2, 1873. 
The President in the chair. Fifteen members present. 
Charles Darwin and Carl Ernst von Baer were elected 
Honorary Members. 
Messrs. A. G. Whitman, J. W. Keene, Chas. H. Andrews, 
Chas. Foster, 8. T. Crosby, Horace B. Plumer, F. C. Bow- 
ditch, L. M. Willis, M. D., and S. F. Whitney, were elected 
Resident Members. ) 
The following paper was read : — 
SomE REMARKS UPON THE AGENCY OF GLACIERS IN THE Ex- 
CAVATION OF VALLEYS AND LAKE-BAsins. By Pror. W. 
H. NILEs. 
Last summer, while spending most of the season among the Alps, 
the point of greatest scientific interest to me was the origin of the 
topographical features of both mountains and valleys. The respec- 
tive geological parts now performed by the meteoric agents, water, 
frost, snow and ice, formed the principal subjects of my study. I 
went there anticipating the pleasure of seeing the glaciers in the 
process of deepening the valleys and possibly of forming rock-basins. 
As to the extent and character of this work I was somewhat disap- 
pointed, and have returned quite a skeptic upon the theories of the 
excavating agency of glaciers. : 
Prof. Ramsay, in’ his theory of the formation of lake-basins, took 
the ground that much of the grinding power of glaciers was at or. 
near their terminations. He maintained that there the ice would 
tend to heap up and attain an unusual thickness, and that the motion 
was not so much by virtue of gravity as by being pushed along by 
the ice descending from the middle, and upper portions. Such con- 
ditions he considered would give the lower ends of glaciers an extra 
erosive power, by which they would, particularly in soft places, exca- 
