LICHENS AND LICHEN. PARASITES

DODGELICHENS AND LICHEN PARASITES 117
Bzbelliu geogrctphica Tuck., Bull. Torrey Bot. Club., 6, 59 ; 1875 : Bull. U.S. Nat. Herb., 3, 30 ;
1876 non (Dill. ex IA.) Tuck., Lich. Calif,, 26 ; 1866.
Rhizocarpon geographiczbm Wilson, Mkm. Herb. Boissier, 18, 88; 1900 : Zahlbr., Deutsche
Siidpolar Exp., 8, 41; 1906 non (Dill. ex L.) Ram. in Lam. & DC.
Type : IZerguelen, Observatory Bay, B.A.N.Z.A.R.E. B192-4.
Thallns uniformis, areolatus, areolis planis vel subconvexis, laevis, viridi-flavus, esorediatus,
hypothallo nigro, tenui, lineam nigram angustam marginalem formans; ecorticatus, stratum
exterum, 35p crassitudine, hyphis medullaribus verticalibns, septatis decompositis; stratum
algarnm protococcoideum (vel cystococcoideum) crassitudine variabili, cellulis sphaerieis, 8-12p,
vel subcylindricis, verticaliter dispositis ; medulla alba, K-, I caerulescens, hyphis 34p diametro,
septatis, verticalibus. Apothecia innato, centralia excentrica vel in areolis marginalia; disco
plano, nigro ad 0.5 mm. diametro; parathecium crasitudine colore variabile; hypothecium vix
evolutum ; thecium 160-180p altitudine ; paraphyses 2-2 -5p diametro, septatae, pachydermeae,
flexuosae, dichotome ramosae anastomosantesque apicibus submoniliformibus incrassatisque,
brunneis, liberis ; asci clavati, 110 X 22p, leptodermei, 8-spori ; ascosporae monostichae dein snbdistichae,
vagina tenui, ellipsoideae, brunneae, muriformes, 29-33 X 15-18~.
Thallus crustose, uniform, areolate, areoles plane or slightly convex, smooth, thin, bright
chalcedony yellow, esorediate, hypothallus black, thin, extending beyond the areoles as a narrow
black line; ecorticate, the outer 35p of decomposing, subvertical, septate medullary hyphae; algal
layer variable in thickness, protococcoid (or cystococcoid) cells spherical, 8-12p in diameter or
ellipsoid to almost cylindrical between the vertical medullary hyphae ; medulla white, K-, I bluish,
hyphae 3-4p in diameter, elosely septate, vertical.
Apothecia innate, variousiy arranged in the areole from central to escentric or even marginal,
rarely occupying the whole areole, disc plane, black, up to 0.5 mm. in diameter ; parathecium of
variable thickness and colour, sometimes 75-80p thick at the margin, thinning to 35p thick below,
the outer black and carbonaceous, shading through fuliginous to hyaline next the thecium,
sometimes thin, 15-20p thick, of thickwalled, slender somewhat dichotomously branched hyphae
in a stiff gel, from very dark fuscous to rarely hyaline, not extending under the hypothecium;
hypotheciuin not clearly differentiated, but the h yphae are somewhat densely tangled and more
deeply staining in a layer about 20p thick just above the blackening vertical medullary hyphae;
thecium 160-180~ tall; para.physes 2-2.5~ in diameter, not closely septate, with gelified walls,
flexuous, dichotomously branched and anastomosing, tips slightly moniliform and thickened,
brownish, free; asci clavate, 110 X 22p, thinwalled, 8-spored (sometimes less by the abortion of
part of the spore nuclei) ; ascospores monostichous, finally subdistichous, with a thin sheath; ellipsoid,
early browning, muriform, 29-33 X 15-18p.
Apparently the species is abundant throughout the islands, the thalli often a centimetre or
less in diamcter when competing with other lichens, and reaching 5 cm. in diameter when not
competing. The development of the perithecium is very variable. It apparently consists of vertical
or somewhat curved hyphae similar to the medullary hyphae with somewhat thicker walls, appressed
or conglutinate, finally dark brown and more or less carbonaceous. In B17744 the parathecium
seems wholly undifferentiated on one side, the hyaline medullary hyphae lying next the paraphyses,
with a few algae extending about one-third under the thecium on that side, while the other side has
a dark brown parathecium about 18p thick ; R90-9 also has a parathecium only on one side and the
thecium is remarkably tall about 250p and narrow, about 250p; the blackening of the medullary
hyphae is also very variable, sometimes only a thin layer under the hypothecium, sometimes extending
to the base of the thallus, while in B177-43 there is no blackening of medullary hyphae, no