284 BOTANICAL GAZETTE ~ foctone: 
society of the similar Jordan sandstone near Mankato, Minnesota,‘ 
However, these last three societies were not so exhaustively studied 
as the first three considered, and a further examination would bring 
to light some of the less conspicuous members of the societies and 
decrease the apparent differences. 
VI. CONCLUSION. 
The facts stated show clearly some very evident adaptations in 
lichen thalli, and as disintegration is going on with comparative 
rapidity at the spot where the society is found, the data herein estab- 
lished will be found useful in future studies. F inally, it may appear 
that undue attention has been given to a society covering a limit 
amount of surface. However, as the writer has stated elsewhere,’ 
it is impossible to deal with the details of the ecologic distribution 
of lichens over a large area, and he has purposely chosen to resttict 
himself, as in this instance, so that certain minute details might 
receive attention. 
Thanks are due Dr. L. H. Pammel for a — of the 
“Ledges.” 
Iowa CoLLEecE, GRINELL, Iowa. 
ichens 
5 Fink, B., Contributions to a knowledge of the lichens of ago Foie : jor. 
of the Miinesots valley and southwestern Minnesota. Minn. Bot. sie4 
18a9. Bryolo- 
6 Fink, B., Ecologic distribution an incentive to the study of lichens. The 
So 
gist 5:40. 1902. 
