664 MINNESOTA BOTANICAL STUDIES. 
It now remains to follow out the ecologic study begun in the 
fifth paper of this series,* pursuing the general plan of study 
introduced there. First of all I shall consider some of the for- 
mations therein recorded and draw some comparisons. As in 
the former paper I shall consider especially the more common 
lichens, which give character to the flora and lichen formations 
of the state. Beginning with the lichen formation of the ex- 
posed granitic bowlders about Battle Lake, the formation may 
be designated as follows: 
LECANORA LICHEN FORMATION OF EXPOSED GRANITIC 
BOWLDERS (BATTLE LAKE). 
Physcia stellaris (L.) Tuck. var. apiola Ny.., C. 
Physcia cesia (Horrm.) Nyu., CX. 
Placodium elegans (Linx.) DC., C. 
Placodium cinnabarrinum (Acu.) Anz., C. 
Placodium aurantiacrm (Licutr.) NAarc. and HeEpp., B. 
Placodium cerinum (HEpw.) NArc. and HeEpp., B. 
Placodium cerinum (HEpw.) NAgc. and Hepp. var. sideritis 
MUCK. 1X. 
Placodium vitellinum (Euru.) NArc. and Hepp., CX. 
Lecanora rubina (VILL.) AcH., CX. 
Lecanora muralis (SCHREB.) SCHAER.var saxicola SCHAER., C. 
Lecanora hageni Acu., C. 
Lecanora varia (Euru.) Nyt., B. 
Lecanora varia (EHRH.) NyL. var. polytropa Nyu., B. 
Lecanora cinerea (L.) SoMMERF., CX. 
Lecanora calcarea (L.) SomMERF. var. contorta FrR., C. 
Lecanora xanthophana Nyu., CX. 
Lecanora cervina (Pers.) Nyt., C. 
Lecanora fuscata (ScHRAD.) Tu. FR., C. 
Rinodina oreina (Acu.) Mass., C. 
Rinodina sophodes (Acu.) Nyu., CX. 
Rinodina sophodes (Acu.) Ny. var. exigua FrR., B. 
Buellia pullata Tucx., C. 
Buellia petrea (FLoT., Kpr.) Tucx., CX. 
Buellia petrea (Fior., Ker.) Tuck. var. montagnei 
Mock... 
* Fink, B. Contributions to a Knowledge of the Lichens of Minnesota.—V. 
Lichens of the Minnesota Valley and Southwestern Minnesota. Minn. Bot. 
Stud. 2: 283-308. 29 D. 1899. 
