—io5— 
sub-linear and much divided, smooth, not wrinkled. Dk. chestnut: 
th. ex. entire. On rocks Parmelia conspersa. 
b. Th. cartilaginous: the lobes mostly broad and rounded, with numerous 
distinct wrinkles on the older portions. (Not commonly fertile ; dk. 
as in the last, th. ex. crenulate or sorediiferous). On trees and 
rocks Parmelia caper ata. 
18. a. Th. commonly reaching a diameter of 10-20 cm. or more, rather 
loosely adherent: lobes flat or concaye, repand, rather narrow, 
becoming reticulately rimose above, densely black fibrillose below, 
the rhizoids reaching the margin. Dk. chestnut: th. ex. rather 
thick, sub-crenulate. Sp. simple, ellipsoid, colorless. On rocks. 
Parmelia saxatilis. 
b. Th. smaller, closely adnate: lobes flat, smooth, rounded and crenate 
or more deeply divided, rhizoids black and extending to the mar- 
gin, but not prominent. Dk. and sp. much as in the last: th. ex. 
mostly thin and entire. On trees and rocks Parmelia tiliacea. 
19. a. Th commonly reaching a diameter of 10-20 cm. or more; lobes 
rounded, flat or concave, somewhat ascendant; becoming reticulate, 
rugose and often with soredia or isidia. Dk. chestnut; th. ex. cren- 
ulate. Sp. simple, ellipsoid, colorless. On rocks and trees. 
Parmelia Borreri. 
b. Th. se'dom more than 5 cm. broad, lobes sub-linear-, convex, often 
overlapping and appressed, smooth, without soredia. Dk. 
brownish-black or gray-pruinose when young; th. ex. mostly entire. 
Sp. bilocular, ellipsoid, brown. On trees, dead wood and rocks. 
Physcia stellaris. 
20. a. Th. mostly dark olive green, without distinct cortical layer. Ap. 
scutellseform Collema* 
b. Th. mostly lead-colored, with a distinct cortical layer. Ap. scutellse- 
form, zeorine or biatorine . Leptogium* 
21. a. Ap. scutellseform or zeorine 22 
b. Ap. cephaloid, stalked: dk. rose-pink or flesh-colored; proper exciple 
(which constitutes the stalk) pinkish-white. Sp. simple, fusiform- 
oblong, colorless. Th. granular, ashy-gray. On the earth. 
Bceomyses roseus. 
c. Ap. lirellseform, branched, innate, black, with or without a th. ex. Sp. 
ellipsoid-fusiform, pluri-locular, colorless. Th. inconspicuous, form- 
ing a very thin, smooth, whitish incrustation on bark. 
Gr aphis scripta. 
d. Ap crateriform, sessile, with a black dk. and proper ex., surrounded 
by an accessory thalline one. Sp. ellipsoid-oblong, bilocular, dark 
colored. Th. greenish-yellow, granular. On dead wood. 
Acolium tigillare 
22. a. Th. drabish-white, becoming rimose or wrinkled. Dk 1-3 mm. broad 
flesh color or pinkish pruinose: th. ex. thick, entire. Sp. simple, 
ellipsoid, colorless mic. On bark Lecatiora pallescens. 
