353 
substrata very favorable to lichen growth. This is particularly 
true of the sandstones, which usually furnish the greatest variety 
of forms, as well as quantity of individual species, Furthermore, 
the Black Hills are very old, geologically speaking, and once cov- 
ered a much greater area than at the present time, with probably 
closer connections with the Rocky Mountains. Alpine and north- 
“érn forms common to these regions very likely came in with the 
same influx of species that sprinkled the mountain tops of both 
sides of our continent with closely allied forms. 
List of Species and Warieties. 
Ramalina pollinaria, Ach. Rocks. Custer City (Bessey.) : 
Usnea barbata (L.) Fr. var. ? always infertile. Trees, Custer City (Ryd- 
berg, Bessey); Rapid City. 
Alectoria jubata (L) Fr. var. implexa, Fr. Trees Custer City (Bessey). 
Theloschistes polycarpus (Ehrh.) Tuckerm. Trees, Rapid City. “a 
Larmelia olivacea (L.) Ach. Common on trees, Custer City (Rydberg); Rapid 
City. : 
Parmelia olivacea ( L.) Ach. var. panniformis, Nyl. Rocks, Custer City (Bessey). 
Parmelia caperata (L.) Ach. Common on trees and rocks. Mostly infertile, ex- 
cept on the latter substrate. Custer City (Rydberg); Rapid City. 
Parmelia conspersa (Ehrh.) Ach. Common on stones. Custer City (Bessey); 
Rapid City. 
Farmelia molliuscula, Ach. High, dry and sterile soil near Rapid City. Also com- 
mon in the Bad Lands of Nebraska and the Dakotas. 
Physcia pulverulenta (Schreb.) Nyl. Trees. Rapid City. 
Physcia pulverulenta (Schreb.) Nyl. var. muscigena (Whinb.) Scher. On earth 
among moss at bases of trees. Custer City (Bessey). 
Lhyscia stellaris (L.) Tuckerm. Trees and rocks. Rapid City. 
Umbiticaria rugifera, Nyl (2). Rocks. Rapid City. 
Umbilicaria As att a ate Plentiful on rocks. Custer City (Rydberg) ; 
Rapid City. : 
Umbilicaria Muhlenbergii (Ach.) Tuckerm., var. @/pina, Tuckerm, Rocks. 
Rapid City; Custer City (Bessey). : 
Umbiticaria vellea (L.) Nyl. Rocks. Rapid City. 
Umbilicaria pustulata (L.) Hoffm. Rocks. Custer City (Bessey). iy 
Sticta amplissima (Scop.) Mass. Trunks of trees and rocks. Custer City (Bes- 
Sey); Rapid City. 
Pultiger ASH REG EN Hoffm. Earth among moss. Custer City (Rydberg); 
Rapid City. eae 
Peltigera horizontalis (L.) Hoffm. Earth, etc. Custer City (Bessey) ; Rapid City. 
Peitigera rufescens (Neck.) Hoffm. Earth, etc. Custer City (Bessey) ; Rapid City. 
Peltigera canina (L.) Hoffm. Earth, ete. Custer City (Bessey); Rapid City. — 
Feltigera canina (L.) Hoffm., var. spongiosa, Tuckerm. Earth among moss in 
deep cafions above Rapid City. 
