Fink : LICHENS OF NORTHWESTERN MINNESOTA. 683 



dent upon the nature of the substratum. To what extent these 

 compounds are of use to the plant, or in what degree they are 

 derived from the substratum is little known. Till these prob- 

 lems are solved we can hardly hope to discuss intelligently the 

 influence of chemical composition upon distribution. 



I am under obligations to Dr. A. Zahlbruckner, of Vienna, 

 Austria, for aid in the determination of several of the species 

 listed below, and also to Dr. E. Wainio, of Helsingfors, Fin- 

 land, for examination and determination of the larger part of 

 the Cladonias. 



LIST OF SPECIES AND VARIETIES. 



1. Ramalina calicaris (L.) FR. var. fraxinea FR. 



On trees, infrequent. Battle lake, June 20, 1900, no. 39. 

 Henning, June 28, 1900, no. 328 and July 2, 1900, no. 412. 

 Thief River Falls, July 18, 1900, no. 796 and July 23, 1900, 

 no. 869. Red lake, July 26, 1900, no. 882 and July 31, 

 1900, no. 1018. 



2. Ramalina calicaris (L.) FR. var. fastigiata FR. 



On trees, frequent. Battle lake, June 18, 1900, no. 2. 

 Leaf hills, June 26, 1900, no. 209 and June 27, 1900, no. 246. 

 Henning, June 28, 1900, no. 330 and 332 and July 2, 1900, no. 

 411. Bemidji, July 5, 1900, no. 471. Thief River Falls, July 

 17, 1900, no. 762. Red lake, July 26, 1900, no. 879 and 

 July 31, 1900, no. 1006. 



3. Ramalina pusilla (PREV.) TUCK. 



On tamarack in swamps, rare. Henning, June 30, 1900, no. 

 370. Bemidji, July 7, 1900, no. 517 and July 8, 1900, no. 

 531. Red lake, July 31, 1900, no. 1012. 



4. Cetraria ciliaris (AcH.) TUCK. 



Common on pines and on tamaracks in swamps. Battle 

 lake, June 20, 1900, no. 71. Henning, June 25, 1900, no. 

 188, June 28, 1900, nos. 315 and 323 and June 30, 1900, no. 

 378. Bemidji, July 4, 1900, no. 427, July 5, 1900, nos. 472, 

 476 and 490, July 7, 1900, nos. 522 and 526, July 12, 1900, 

 no. 680 and July 14, 1900, no. 730. Red lake, July 28, 1900, 

 no. 463, July 30, 1900, nos. 985 and 988, August 2, 1900, no. 

 1050 and August 3, 1900, no. 1070. 



5. Cetraria juniperina (L.) ACH. var. pinastri ACH. 



On pines and on tamaracks in swamps, rare. Bemidji, July 



