— 103 — 
b. Branches flattened, often isidiiferous, ashy-gray above, paler or often 
black spotted below. On trees and dead wood (mostly sterile). 
Everina furfuracea. 
9. a. Branches flattened 10 
b>. Branches terete 11 
10. a. Branches involute, beset at the margin with a row of dark- colored, fin- 
ger-shaped projections, 0.3-0. 5 mm. long (containing the sperma- 
gones). Th. mostly brown above, lighter towards the base where 
there is sometimes a red stain. Ap. (infrequent) scutellseform, dk. 
chestnut. On the earth. (The “ Iceland Moss ” of druggists.) 
Cetraria Islandica. 
b. Branches scarcely involute, often with slender projections at the mar- 
gin, but these are sharp-pointed, yellowish or gray like the th., 
usually exceed 1. mm., in length and do not contain sperm agones. 
Ap. scutellseform; dk. brown orange ; th. ex. often radiately fibri- 
lose On trees and rocks Theloschistes chrysophthalmus. 
c. Branches not involute, without spermagone-bearing projections differ- 
ing in color from the th. which is pale greenish or straw-color, rather 
rigid, more or less reticulately-lacunose and quite variable in the 
form and number of its divisions, Ap. scutellseform; dk. pale, not 
differing much from the th. in color. Mostly on trees. 
Ramalina calicaris. 
11. a. Th. greenish, covered with numerous fibrils of the same color: 
medulla consisting of- a cottony layer surrounding a tough central 
cord. Ap. scutellseform; dk. pale; th. ex. radiately fibrillose. On 
trees (called “ Bearded Moss ”) Usnea barbata . 
b. Th. dark brown, smooth, sometimes with pale soredia: medulla uni- 
form throughout. Ap. (rare) scutellseform, small. Mostly on trees 
and dead wood Alectoria jubata. 
c. Th. ashy-gray, the branches clothed with granules which may become 
coralloid or scale-like; medulla firm and uniform throughout. Ap. 
cephaloid, dark brown or black. On rocks or on the earth. 
Stereocaulon .* 
12. a. Th. umbilicate 13 
b. Th. frondose ... 14 
c. Th. appressed, the margin sometimes ascendant 15 
13. a. Th. cartilaginous, pale brown or ashy above, fawn-color to dark-brown 
below, smooth on both surfaces, lobes sometimes much crowded and 
overlapping. Ap. angiocarpous, imbedded in the th. On rocks, 
near water so as to be occasionally submerged. 
Endocarpum mineatum. 
b. Th cartilaginous, ashy-color above, whitish toward the center; below 
pale brownish or ash-colored; smooth on both surfaces, often pruin- 
ose; with numerous pustular protrusions above, having correspond- 
*Of genera thus marked we have several species, the discrimination of which is too 
difficult to be considered here. 
