BULLETIN 
TORREY BOTANICAL CLUB. 
Lichens of the Black Hills and their Distribution.* 
By THOMAS A. WILLIAMS, 
The thoughts presented in this paper are based upon a short 
study of the specimens in three collections from the Black Hills of 
South Dakota. The first of these was made by Dr. C. E. Bessey 
in the summer of 1891 at Custer City; the second by myself in 
August of the same year in the region surrounding Rapid City; 
and the third by P. A. Rydberg during the summer of 1892 
mainly at and near Custer City. 
One of the first points brought out by a study of the lichen 
flora of the Black Hills is that the number of rock lichens is, com- 
paratively, very large, while tree-loving species are very Scarce. 
Of the 83 species and varieties determined, 44, or more than 53 
Per cent., have so far been found on rocks only; 22, or nearly 27 
Per cent., grow on earth, while but 8, or less than 10 per cent., are 
found growing on trees exclusively. Six forms occur on both 
trees and rocks, one on both earth and rocks, one on both earth 
and rotten logs, and one parasitic on the thallus of various — 
Cladoniz. 
_ Comparing this with a list of lichens found in Eastern Ne- 
braska, the difference is at once seen to be quite striking. In this 
i latter list, which consists of 115 species and varieties, 32, or nearly 
28 per cent., grow on rocks; 68, or nearly 58 per cent, grow on 
—*Read before the Section of Botany, A. A. A. Ss. Madison Meeting, August, 1893. : 
