— iog — 
Eastern Continent it is found in high latitudes, Brotherus (Die Natiirlischen 
Pflanzenfamilien, i, 3:438, 1902) gives its range as Norway, North Finland 
and Lapland, Beeven Island and Spitzbergen, also Siberia, near the mouth 
of the Yenisei River. Several of these stations are north of the Arctic Cir- 
cle. It appears on the Western Hemisphere within the Arctic Circle at 
Clavering Island off the coast of Greenland and nearest the two above men- 
tioned island stations north of Europe. On the mainland it has been mostly 
found in the western part of British America. Macoun gives as its range 
“ Rocks and banks amongst the Rocky Mountains, Drummond. Crevices 
of rocks, Ont. ; on wet rocks near Hector and at the ‘ Gap,’ Rocky Moun- 
tains; also on the bank of the Columbia River at Revelstoke, B. C., 1890, 
MacounP (Catalogue of Canadian Plants, Musci, p. 96, 1892.) It was the 
moss from Hector, B. C., that I had for comparison (Can. Mus. No. 365). If 
we follow Brotherus in identifying E. Selwini Aust. as E. procera Bruch, 
then Vancouver Island (Victoria at the south end) and some more northerly 
stations will be included. The station in the above range nearest to Presque 
Isle is Lake Nepigon, north of Lake Superior, about two hundred and fifty 
miles away. Its presence on the south shore of Lake Superior would be 
natural enough in a climate more severe than parts of British Columbia and 
especially Vancouver Island. It is harder to account for it in northern Illi- 
nois, but it is only one of a number of northern plants that find a congenial 
home near the south end of Lake Michigan. It is the southern limit of rang-e 
for Pinus divaricata , the Jack Pine. Other plants of the vicinity are 
Linnaea borealis , Betula papyrifera, Salix adenophy lla, Equisetum scir- 
poides, Aster ptarmicoides lutescens. 
A factor of great weight in accounting for the southern distribution of 
boreal plants is their relation to former lines of drainage. The locality at 
Lockport is on the outlet of Lake Michigan where its water, together with 
those of the upper Lakes, went southward to the Mississippi. It is a glacial 
made valley through which now flows a small river, the Desplaines. The 
cliff is vertical, the base covered by thallus, the top forty or more feet higher 
than the glaciated rock-bed of the valley. Except by the slow process of 
weathering to which the plants readily conform, the upper part of such a 
mass would be unchanged since the ice-sheet left it. The lower part would 
be subject to the wear of the water of the outlet. That plants migrate from 
the north during the cold of the ice-age is now a common concession. That 
they withdraw as the ice receded is equally granted, such being left as could 
adjust themselves to changed climatic conditions. There is no objection, 
based on climate, to the presence of plants in northern Illinois that are found 
on the south shore of Lake Superior or in the parts of British Columbia and 
Vancouver Island near the Pacific Coast, and there is little probability that a 
moss sheltered as on the rocks at Lockport once established, would be sub- 
ject to extinction by violence. There is no evidence to show that they were 
liable to overflow by the former outlet of the lakes. As now constituted there 
is a valley cut in the limestone at this point forty feet deep and a mile and a 
quarter wide. Only a very narrow part of it has been deepened by the river 
