LICHENS AND LICHEN. PARASITES

260 B.A.N.Z. ANTARCTIC RESEARCH EXPEDITION
the centre thinning to 2-8a at the edges of the iheciam where it merges with the cortical cells,
pseudo-parenchymat~~s with a tendency to periclinal arrangement; thecium 901-llOr tall ; paraphyses
2a in diameter, branched or unbranched, septate, thick-walled, apical cell 4r in diameter,
darkened at the surface; asci short clavate, 8-spored, 3646 X 14.5-17p; ascospores dark brown.
2-celled, obtuse, rarely or only slightly constricted at the septum, sometimes undivided, 9-13 X
5-8~.
Spermogonia immersed in the thallus, from flask-shaped to quite irregular ; wall thin, hyaline
of very small-celled pseudoparenchyma; spermatiophores about 10 X lr, few septate, branched;
sprmatia ellipsoid, about 4 X lr.
There is considerable variation of colour from ashy-fuscescent, through ashy to almost white,
although the marginal areoles are always dark, but none of the colour variations is correlated with
microscopic characters, the thickness of the thallus nor with the ease with which the as~imilative
areoles separate from the hypothallus, leaving bare patches. As colonr and interrnpted thallus and
its thickness are the only characters used by Darbishire to separate B. quercina Darb., Brit. Nat.
Antarct. "Discovery" Exp. Nat. Hist., 5, I~ich., 8; 1910, from this species, I am inclined to think
he had two extremes of a continuous series, although I have not seen his material. Many of our
specimens agree microscopicallv in all characters except darkening of the outer cells of the cortex
below the amorphous layer (secondary cortex of Darbishire). As in specimens with these cells
darkening, one finds areas where they are just forming and have not darkened, I have assumed
that the specimens~vithont darkening of the cortical cells are only younger states of the same species,
although the apothecia have already developed.
The systematic position of this species has always been a puzzle. The structure of the apothecium
is clearly that of a lecanorine apothecium. The algae are present in the young stages as
Darbishire reported in the original description and as I have observed repeatedly. As the algae
die and disappear, the mednllary hyphae become brown, giving the appearance of a lecideine apothecium,
if little attention is paid to details of the tissues surrounding the thecium. Until we have
more accurate definitions of lecanorine and lecideine, and these terms are more accurately applied,
such species as this will be troublesome. As Dr. Baker and I saw only two old specimells from
Marie Byrd Land, we left the species in Buellia, but the abundance of material from these three
expeditions shows clearly that it belongs in Rinodina sect. Beltraminia,
On rocks with Toninia Johnston~i, Unzbilicaria Hunteri, U. rugosa, U. s~c.bcerebriformis, Charcotia
cerebriformis, Lecanora exsulanp and its forma minor, L. JoJLnstoni, CaadelurhUa cerebriformis,
Usnea sp., Protoblastenin citrina, Polyca~iliona citrina and Xanthoria Mawsomi.
South Victoria Land : Cape Royds, D. Mawson 1058 (Brit. Antarct. [Shackleton] Exp.).
King George V Land : Horn "Dreadnought ' ' Bluff, A. L. McLean, A.A.E. 32 ; Cape Denison,
A.A.E. 141, 166, 172, 185, 188, 189, 190, ,191, 192, 193, 1049-2; B.A.N.Z.A.R.E. 536-7, 536-8,
536-9, 53610, 536-11, 536-14, 536-18, 536-24, 53627, 536-28, 536-32, 536-36, 536-37, 53640,
53641, 53643, 536-44, 53645, 53647, 53648, 53649, 53650, 536-51, 53652, 536-53, 53654,
536-55, 53656, 536-57.
Queen Mary Land : Hippo Nunatak, C. T. Harrisson, A.A.E. 35.
MacRobertson Land : Cape Bruce, B.A.N.Z.A.R.E. 108-13, 108-14, 108-29, 108-30, 108-31,
1O8-32,1O8-33,108-34, 108-35, 10840, 10841, 10842 ; 1847.