14 OTTO VERNON DARBISHIRE, (Schwed. Südpolar-Exp. 



sed vulgo non bene visus; apothecia nigra minuta, ad 0.25 mm lata; primum thallo 

 immersa, dein paulo elevata; discus niger, nudus; parathecium et hypothecium 

 hyalinum; sporae octonae, bicellulares, fuscae, 18 — 20 X 8 — 10 n magnae; habitat 

 ad saxa, Graham Land, Louis Philippe Penins., Hope Harbour. 



Notes: The most characteristic feature of this species is the great thickness of 

 the thallus and its light colour. The plant is not of great size and seems cramped 

 although it has not developed to its fullest possible extent. 



Buellia discreta nov. spec. 



(Plate 3, fig. 25.) 



Thallus tenuissimus, continuus et parce rimulosus aut indistinctus et quasi nullus, 

 sordide fuscescens, K flavescens; hypothallus nigricans sed non nisi indistincte visus; 

 apothecia nigra, emergentia, lecideina, margine proprio instructa semper bene viso, 

 disco piano, rotundata aut parce difformia, 0.2—0.4 mm lata; epithecium et parathe- 

 cium carbonaceum; hypothecium fuscescens; sporae octonae, fuscae, bicellulares, 

 12 — 16x6 — 10 fi magnae, medio non constrictae, apicibus rotundatis; spermogonia 

 nulla visa; habitat ad saxa argillacea, Falkland Islands, Port Louis. 



Notes: This species is very distinct and is recognised by the very simple thallus 

 which is only a shade lighter than the colour of the substratum. The apothecia 

 always show the proper margin well developed and only indistinctly can the areo- 

 lation of the thallus be made out. 



Buellia falklandica nov. spec. 



(Plate 3, fig. 26.) 



Thallus crassiusculus, laevis. continuus, distincte rimoso-diffractus, albidus aut 

 albido cinerascens, bene delineatus; hypothallus nullus visus aut lineam nigram te- 

 nuissimam formans; apothecia nigra, primum thallo immersa urceolata sed mox 

 emergentia et margine instructa bene evoluto, disco piano rarius convexo, 0.2 — 0.5 

 mm lata; epithecium et parathecium carbonaceum; hypothecium nigrofuscum; sporae 

 octonae, juniores simplices et vetustiores bicellulares, fuscae, 18 — 24x8 — 12 \.i magnae, 

 medio non constrictae, apicibus rotundatis; spermogonia nulla visa; habitat ad saxa, 

 Falkland Islands, Port Louis. 



Notes: This species is distinguished by its continuous thallus which is well sepa- 

 rated from the substratum, and from any neighbouring lichens. A black margin is 

 really only well seen when the plant comes into contact with other lichens but 

 otherwise the black hypothallus is hardly distinguishable. The black proper margin 

 of the apothecium is well marked as in the previous species. 



