PRINCIPLES OF BIOLOGY. 
197 
objection to Mr. Herbert Spencer’s views of life, and there¬ 
fore to the whole system of Biology which he has built upon 
them. 
So far as my limited judgment can go, the difference 
between Darwin and Spencer is pretty much the same as that 
between history and fiction. 
Birmingham, June 11th , 1884. 
ICE ACTION IN THE VALLEY OF THE AKTKO. 
This valley trends westward to the sea, through the district 
called Ardudwy, comprising a large part of the county of 
Merioneth, near Harlech, between mountains and sea, a tract 
notable for its number of Cromlechs and Druidical remains 
of several kinds. But I wish to call attention to some re¬ 
markable evidences of Ice Action in this particular valley, 
below the ancient Pass through the mountains, a narrow 
ravine called Bwlcli Drws Ardudwy, of surpassing rugged¬ 
ness and grandeur. Below the Pass, where the valley begins 
to widen, and especially as you stand at the upper bridge 
spanning the rapid Artro, nearly the whole of the many 
bare rock surfaces are seen to be strikingly glaciated, the 
smootliened faces curving often slightly over, away from the 
Pass, in the direction the ice must have taken. Passing 
recently three times through the valley, I stayed to examine 
the rocks. One long surface, inclined at a considerable angle, 
I measured to be about sixty-four paces long, or perhaps 
about sixty yards, planed over most smoothly and having a 
number of large grooves, some of nearly semi-circular section, 
and two inches or more in width, generally straight, and 
often crossing the old cracks in the rocks—a very fine ex¬ 
ample of an ice-planed surface. Others are of various lengths, 
many long, scattered about the entire upper valley, and 
generally rough and broken only on the side fronting approxi¬ 
mately down towards the sea, affording a most marked 
contrast to the surfaces towards the mountains. This valley 
becomes a little lower down of a width of half a mile or more, 
before the ordinary tree-clad glen is reached, and is so long 
as to contain the sites of the three old Tarns now silted up; 
and across this the glacier must have spread, up to a great 
height. Scattered about, and often catching the eye by their 
peculiar positions, are many great blocks brought down from 
the mountains. One I measured is about 7 feet x G feet 
3 inches x 4 feet 4 inches, and rests on a bare rock. Just 
beyond is a picturesque fall of the beautiful Artro, rushing 
