98 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 
PLACOLECANIA (Steiner) Zahlbr. 
Thallus crustaceous; spores 2 to 4-locular; sterigma simple or branched, endo- 
basidial. 
1. Placolecania candicans (Fries) Zahlbr. in Engl. & Prantl, Nat. Pflanzenfam, 1!*: 
205. 1907, 
Lichen candicans Dicks, Pl. Crypt. Brit. 8: 15, 1793. 
Thallus whitish, mealy, forming round patches, areolate-rimose in the center or 
squamulose, the scales somewhat dispersed and then lobulate, at the circumference 
becoming lobulate-radiate, KHO—; apothecia sessile; disk dull brown black, with 
a faint bloom and with a turgid, finely crenulate thalline margin; epithecium gray- 
ish brown, subcontinuous; thecium colorless, 96 to 102 thigh, with iodine deep blue; 
paraphyses coherent, strict, not septate nor forked, the tips capitate and slightly 
colored; hypothecium nearly colorless or with a very faint yellowish tint; asci clavate, 
8-spored ; spores oblong-ellipsoid, 11 to 17 » long, 4 to 5 # thick; spermatia staff-shaped, 
4 to 8 » long, 1 » thick; sterigma straight, simple; gonidial layer extending under the 
hypothecium. 
On calcareous rocks, Santa Catalina Island, and argillaceous shale in the Santa 
Monica Range. 
PHLYCTIS Wallr. 
Thallus crustaceous, thin, spreading, scaly-pulverulent; apothecia persistently 
immersed, the thalline margin irregularly lacerate; asci 1 or 2-spored; spores color- 
less, oblong-ellipsoid, muriform, the epispore thin; sterigma simple; spermatia elon- 
gate, straight. 
KEY TO SPECIES. 
Spores with blunt, rounded ends........................-.-..... 2. P. argena. 
Spores with an acuminate cell at each end....................... 1. P. agelaea. 
1. Phlyctis agelaea (Ach.) Koerb. 
Thallus subdeterminate, thin, white or oftener grayish white, mealy, KHO-+-yel- 
low, then red; apothecia very small; disk black, white-pruinose; thalline margin thin, 
white, pulverulent; epithecium yellowish brown, granulose, with KHO- orange 
brown; thecium 120 » high, colorless, with iodine the hymenial gelatine yellowish, 
the ascus wall permanently blue; paraphyses separate; hypothecium similar to the 
epithecium, with iodine brown; asci ventricose, 88 « long, 24 # thick; spores 2 or 
sometimes solitary, muriform-multilocular, decolorate, at each end a small but dis- 
tinct apical, acuminate cell, 48 to 84 » long, 14 to 20 » thick, with iodine staining 
yellow to orange; sterigma simple; spermatia short, straight. 
On barks (Populus trichocarpa and Salix lasiolepis) in canyons of the Santa Monica 
Range; on Acer macrophyllum in the San Gabriel Range. 
2. Phlyctis argena (Ach.) Koerb. 
Thallus thin, white, smooth or slightly rugulose, effuse, KHO-+ yellow, then red, 
particularly the thalline margin; hypothallus pallid; apothecia adnate, small, not 
exceeding 0.5 mm. in width; disk brown black to black, flat; thalline margin white, 
pulverulent, crenulate, often thickly pruinose, semitranslucent when moist; epithe- 
cium granulose, yellowish; thecium colorless, 104 to 140 # high; paraphyses separate, 
simple, not thickened at the adglutinated apices; hypothecium colorless or dingy 
brown; asci 169 yw long, 80 » thick; spores solitary, 100 to 140 # long, 44 thick, color- 
less, muriform, oblong, with rounded ends; with iodine the asci staining blue and 
the spores yellow. 
On barks, Santa Cruz Mountains, Herre; in the canyons of the Santa Monica and 
San Gabriel Ranges. 
