LICHENS AND LICHEN. PARASITES

DODGE-LICHENS AND LICHEN PARASITES 77
of Psoron~a as a section by Acharius and later authors and to Psormta Gray and Nylander and
implied by Michaux although not expressed, it may be chosen to conserve Psorma in its present
llsage, without conflict to historical principles of nomenclature. Since Michaux added nothing
to Acharius' treatment as a section nor intended to give a complete treatment of the group, to
select P. microphylla (Sw.) Michx. would replace Parnteliellu by Psoron~a, or to select P. pa!mihlata
Michx. would replace Anaptychia Mass. by Psorornn, either cour~se resulting in much confusion
of nomenclature.
Thallus squanlose to somewhat foliose, rhixinae slightly developed or absent; heteromerous,
withont tomentnm, upper cortex of vertical septate hyphae forming a pseufiparenchyma,
rarely of irregularly arranged hyphae ; algae Dactylococczbs 1; medulla loose ; lower cortex of periclinal
hyphee. Apothecia sessile, lecanorine, constricted at the base; hypothecium hyaline; paraphyses
usually simple; ascospores m~icellular, spherical to ellipsoidal, thin-walled; spermatic
phores septate; spermatia short, straight.
Psoroma hirszttzhlzhm Nyl. in Crombie, Jour. Bot. Brit. For., 13, 333; 1875. Jour. Linn. Soc. Bot.,
15, 184; 1876. Phil. Trans. Roy. Soc. [London], 168, 48; 1879. Rept. Sci. Results Voy.
"Challenger" Bot., 1, 2, 234; 1885. Bouly de Lesdain, Ann. Crypt. Exot., 4, 100; 1931.
Type: Kerguelen, Observatory Bay, A. E. Eaton (Venus Transit Exp.) on mosses and
decayed stems of Acaem.
Thallus little developed between the apothecia; apothecia crowded, reddish brown, concave,
1-2 mm. in diameter, amphithecinm densely whitish hirsute or woolly; ascospores 16-21 X 9-14~.
We have seen no material referable here. There seems little to distinguish this species from
Lecanora broccha Nyl. except the larger spores, since the latter may belong in Psoronta.
Psoronaa versico1o1- Miil1.-Arg., Flora, 71, 538; 1888.
Lecanora versicolor Hook. f. & Tayl., London Jonr. Bot., 3, 642; 1844 non Aeh.
Type: Lord Auckland's group, J. D. Hooker (Voy. "Erebus & Terror") [on old wood me
Muller-Argau] .
Thallus of concrescent squamu~es, growing over tops of mosses, surface smooth or minutely
g~anular, margin subeffigurate, of short rounded lobes about 1 mm. broad, yellowish glaucous;
cortex 35-5OP thiek, of fastigiate hyphae, gp, lumen Ip in diameter, branched and anastomosing
(the deeply staining lumina forming a reticulum which might be mistaken for boundaries of
~seudoparenchymatous cells), partially conglutinate ; algal layer about 70p thick, of snbspherical
colonies and single cells 8p in diameter, separated by strands of closely woven medullary hyphae;
medulla about 5OP thick, of more loosely woven, subvertical hyphae 6-7p in diameter, very thickwalled,
somewhat more periclinal below between the rhizinal hyphae, but not forming a cortex.
Apothecia very numerous, about 1.5 mm. in diameter, constricted below, margins inrolled,
smooth concolorous with the thalhs, disc very concave, buffy olive or darker; amphithecium
200p thick below, thinning to 100p thielp above, cortex 50p thick, of the same structure as that of
the thallus, but the hyphae slightly more &lender and less anastomosed, thinning rapidly at the
top; algal layer filling the rest of the amphithecinm, in less compact colonies above, more scattered,
solitary cells below and disappearing under the hypothecium ; hypothecium 40p thick below
thinning to 20p at the edges, of conglutinate, hyaline, periclinal hyphae, not otherwise differentiated
from the medulla; thecium 130p tan; paraphyses about lp in diameter, unbranched or