LICHENS AND LICHEN. PARASITES

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B.A.N.Z. ANTARCTIC RESEAliCII EXPEDITION
densely packed with algal cells arranged in radial rows which also fill the lacunae in the outer
surface of the axis, medullary hyphae few, radiating from the axis and producing the cortex ; chondroid
axis about 950,~ in diameter, similar in structure to that of C. Taylori.
The ahove description is based on the Heard Island material, which differs slightly from
Lamb's description in being somewhat smaller with a thinner cortex and relatively thicker axis.
The cortical hyphae form a more regular palisade. The algae are similar to those of U. Taylori and
U. floriformis. In several respects, these species are transitional between the subgenous Neuropogon
and the subsection Roccellinae, having the colour of the former, but microscopic structure of
the latter.
Heard Island : between Atlas Cove and Corinthian Ray, B.A.N.Z.A.R.E. B140-50.
TJSNEA CROMBII Dodge, sp. nov.
? Nez~rqwgon melaxuunlthus v. sorediifer Crombie, Jour. Linn. Soc. 13ot., 15,182 ; 1876 : Phil. Trans.
Roy. Soc. [London], 168,47 ; 1879.
? Usnea melaxantha v. swediifera Wilson. B44m. Herb. Bossier, 18, 87; 1900, probably non Miill.-
Arg.
? ITsnea sdphurea v. soredifera Zahlbr., Deutsche Siidpolar Exp., 8,52; 1906, probably non Vain.
f Neitropogon antarcticus v. sorediifer Lamb. Jour. Cinn. Soc. Rot., 52, 213 ; 1939.
Type: Heard Island, between Atlas Cove and Corinthian Ray, B.A.N.Z.A.R.E. R140-36.
Thallus growing in dense tufts about 5 cm. tall and broad, branching dichotomous, interiiodcs
relatively short and about equal throughout the length, branches somewhat flexuous, the ultimate
branches often carved, younger ones slender with acute tips, older much less attenuate and tips
obtnee; base blackened, about 1 mm. in diameter, isabella colour to honey yellow, upper portion
more or less black, maculate sometimes black annulate but not cracked; surface variously rugose
and somewhat foveolate, with abundant irregularly distribnted verrucae or short papillae, often
forming minute soredia at their tips, verrucae fewer but somewhat larger near the tips, with soralia
more eroded; cortex 36-55p, rather variable in thickness in the same section, a palisade of thick-
walled, gelified hyphae about once dichotamous above, completely structureless in the upper lop;
medulla K brown, soon fading to colourless, about 100p thick up to 200p under the verrucae, of
densely woven, thick-walled hyphae with aggregations of relatively large crystals in the lower
half; algae in dense colonies, occupying the whole thickness of the medulla, or confined to the
upper half with some single cells scattered throughout the medulla, filamentous, branched,
bright orange in section, cells relatively short cylindric, becoming subspherical when occurring
singly; chondroid axis about 625p in diameter, of thick-walled, branched, conglutinate hyphae,
leaving irregular lacunae near the centre, but not conspicuously hollow.
The interpretation of Neuropogm melaxmthzu v. sorediifer Crombie is very difficult, as the
type has never beell adequately described. Votyka states that some forms from Kerguelen (i.e.
Crombie's specimens of N. melaxanthus v. sorediifer) seem to approach U. mromelam4. Our plants
have rt cortex somewhat cracked into areoles near the base, but without blackening in the cracks as
in U. acromelam, and none of the characteristic annular cracks. The surface of the branches is
also somewhat reminiscent of U. strigdosa. Lamb, on the other hand, emphasizes the reactions
with potassium hydroxide and paraphenylene diamine. Our plants apparently have less of the
colour-producing compounds than Crombie's type, but more than other plants which Lamb refers
here.