720 MINNESOTA BOTANICAL STUDIES. 



48. Placodium citrinum (Hoffm.) Leight. 



On calcareous rocks, probably rare. July 11, 1896, no. 150a; 

 July 30, 1896, no. 204. 



Not previously reported from Minnesota. 



49. Placodium aurantiacum (Light.) Naeg. and Hepp. 



On trees and calcareous rocks, frequent. June 26, 1896, no. 

 30; July 2, 1896, no. 52. 



50. Placodium ceriiium (Hedw.) Naeg. and Hepp. 

 On trees, abundant. July 12, 1896. no. 193. 



The usual form occurs, and also another with whitish thalline 

 exciple and sub pruinose apothecia. The last, usually on 

 Ulmus, is, I think, worthy of a distinct name, though thus far 

 always included with this species. 



51. Placodium cerinum (Hedw.) Naeg. and Hepp. var. py 



racea Nyl. 

 On dead wood, frequent. July 12, 1896, no. 193a. 

 Not previously reported from Minnesota. 



52. Placodium cerinum (Hedw.) Naeg. and Hepp. var. sid- 



eritis Tuck. 

 On granitic rocks, frequent. June 26, 1896. no 11. 

 Not previously reported from Minnesota. 



53. Placodium vitellinum (Ehrh.) Naeg. and Hepp. 

 On wood, infrequent. July 10, 1896, no. 147. 

 Spores nearly all simple, scarcely exceeding 8 in asci. 



54. Placodium vitellinum (Ehrh.) Naeg. and Hepp. var 



aurellum Ach. 



On calcareous and granitic rocks, frequent. June 28, 1896. 

 no. 54; July 3, 1896, no. 73. 



Spores 8 in asci, and always 2-celled in the specimens on cal- 

 careous rocks. On granitic rocks spores are 8 in asci, but fre- 

 quently simple. 



Not previously reported from Minnesota. 



55. Lecanora rubina (Vill.) Ach. 



On granitic rocks, rare. July 13, 1896, no. 206 



56. Lecanora muralis (Schreb.) Sch^er. var. saxicola ScHyEr. 

 On granitic rocks, rare. June 24, 1896, no. 1. 



Not previously reported from Minnesota. 



57. Lecanora subfusca (L.) Ach. 



On trees, infrequent. July 4, 1896, no. 94. 

 A common lichen in northern Iowa, but about Minneapolis it 

 is confined to damp woods — a result of dryer climate. 



