690 MINNESOTA BOTANICAL STUDIES. 
56. Collema ryssoleum Tuck. 
On Populus, rare. Bemidji, July 12, 1900, no. 686. 
Not previously reported from Minnesota. 
57. Collema pulposum (BERNH.) Nyt. 
On earth, rare. Battle lake, June 20, 1900, no. 77. Leaf 
hills, June 26, 1900, no. 207. Henning, June 29, 1900, no. 
352. Léaf-hills, July. 2,.1900, no. 400, , Bemidji, Julygs. 
1900, no. 477. Thief River Falls, July 17, 1900, nos. 769 and 
779. 
58. Collema crispum Dorr. 
On earth, frequent. Bemidji, July 11, 1900, no. 605. 
59. Collema limosum Acu. 
On earth, infrequent. Bemidji, July 10, 1900, no. 568, 
July 11, 1900, no. 637 and July 14, 1900, no. 736. 
Not previously reported from Minnesota. 
60. Leptogium lacerum (Sw.) Fr. 
On earth, rare. Leaf hills, June 27, 1900, no. 287. Thief 
River Falls, July 18, 1900, no. 795. 
61. Leptogium myochroum (EuruH., SCHAER.) TUCK. 
On trees and rocks, rare.. Battle lake, June 21, 1900; no: 
123 and June 23, 1900, no. 156. Henning, June 30, 1900, nos. 
381 and 382. Bemidji, July 5, 1900, no. 485 and July 173, 
1900, no. 7IO. 
62. Placodium elegans (Linx.) DC. 
On granite and limestone, rare. Battle lake, June 20, 1900, 
nos. 60 and 66. Bemidji, July 11, 1900, no. 638. Thief River 
Falls, July 17, 1900, no. 776. 
63. Placodium murorum (Horrm.) DC. 
On lime bowlders, rare. Thief River Falls, July 9, 1900, 
no. 825. With deficient thallus. 
64. Placodium cinnabarrinum (Acu.) ANz. 
On granite rocks, infrequent. Battle lake, June 20, 1900, 
nos. 45 and 50. Leaf hills, June 27, 1900, nos. 276 and 282. 
65. Placodium aurantiacum (LicuTr.) Narc. and Hepp. 
On trees and granites, infrequent. Battle lake, June 19, 
1900, no. 37. Leaf hills, June 27, 1900, no. 253. Bemidji, 
July 11, 1900, no. 643. Thief River Falls, July 19, 1900, no. 
