222 MINNESOTA BOTANICAL STUDIES. 



count I have been compelled to select very small islands, though 

 not offering so much diversity as to substrata, and have even 

 then confined the analysis to the lithophytic and a few epigean 

 species. 



For this study of islands three were selected in the Snowbank 

 lake area, and the lithophytic species were carefully noted on 

 two of them and on the other also the decrease in number due 

 to the establishment of an arboreal flora. It is to be regretted 

 that the study could not have been extended to more islands and 

 to include epiphytic and epigean species as well as lithophytic. 

 Island number one is situated in Sucker lake, 30 feet from the 

 shore, in the N. W. 14: of S. W i^ of S. E. ^ of Sec. i, T. 64 

 N., R. 9 W. The size of the island is about 70x75 feet. The 

 surface is rocky with soil in a few places formed in situ or 

 washed in from the lake, so that Cladonias were well estab- 

 lished. About twenty shrubs were growing on the island and 

 two rather small pines. The species noted in a short time are 

 as follows : 



1. Cladonia rangiferina (L.) Hoffm. 



2. Cladonia rangiferina (L.) Hoffm. var. sylvatica L. 



3. Cladonia rangiferina (L.) Hoffm. var. alpestris L. 



4. Cladonia pyxidata (L.) Fr. 



5. Cladonia gracilis (L.) Fr. 



6. Cladonia uncialis (L.) Fr. 



7. Stereocaulon paschale (L.) Fr. 



8. Umbilicaria muhlenbergii (Ach.) Tuck. 



9. Endocarpon fluviatile DC. 



10. Parmelia conspersa (Ehrh.) Ach. 



11. Parmelia saxatilis (L.) Fr. 



12. Parmelia caperata (L.^ Ach. 



13. Physcia sp. 



14. Physcia stellaris (L.) Tuck. 



15. Physcia speciosa (Wulf., Ach.) Nyl. 



16. Physcia obscura (Ehrh.) Nyl. 



17. Ephebe solida Born. 



18. Pannaria microphylla (Sw.) Delis. 



