LICHEN COMMUNITIES 377 



The following were noted by Lesdain and other workers : 



On iron X author ia parietina, Physcia obscura and var. virella, Ph. 

 ascendens, Placodium (flavescens) sympageum, PL pyraceum, PI. citrinum, 

 Candelariella vitellinum, Rinodina exigua, Lecanora campestris, L. umbrina, 

 L. galactina, Lecania erysibe, Bacidia inundata. Xanthoria parietina is one 

 of the commonest wandering species; it was found by Richard 1 on an old 

 cannon lying near water, that was exfoliated by rust. 



On tar Lecanora nmbrina. 



On charcoal Rinodina exigua, Lecanora umbrina. 



On bones Xanthoria parietina, Physcia ascendens, Ph. tenella, Placodium 

 citrinum, PI. lacteum, Rinodina exigua, Lecanora galactina, L. dispersa, L. 

 nmbrina, Lecania erysibe, L. cyrtella, Acarospora pruinosa, A. Heppii, Bacidia 

 inundata, B. muscorum, Verrucaria anceps, V.papillosa. 



In Arctic regions in Ellesmere Land and King Oscar Land, Darbishire 2 

 found on bones : Lecanora varia, L. Hageni, Rinodina turfacea and Biiellia 

 parasema (disciformis). He could not trace any effect of the lichens on the 

 substratum. 



On charcoal Rinodina exigua, Lecanora umbrina. 



On dross or clinkers Parmelia dubia, Physcia obscura, Ph. ascendens 

 f. tenella, Ph. pulverulenta, Xanthoria parietina, Placodium pyraceum, PI. 

 citrinum, Rinodina exigua, Lecanora dispersa, L. umbrina, Lecania erysibe. 



On glass 3 Physcia ascendens f. tenella, Buellia canescens. Richard has 

 recorded the same lichens on the broken glass of walls and in addition : 

 X anthoria parietina, Lecanora crenulata, L. dispersa, Lecania erysibe, Rinodina 

 exigua, and Buellia canescens. 



On earthenware, china, etc. Physcia ascendens f. tenella, Lecanora 

 umbrina, L. dispersa, Lecania (? Biatorind) cyrtella, Verrucaria papillosa, 

 Bacidia inundata. 



On leather Nearly fifty species or varieties were found by Lesdain on 

 old leather on the dunes. Cladonias, Parmelias and Physcias were well re- 

 presented with one Evernia and a large series of crustaceous forms. He 

 adds a note that leather is an excellent substratum : lichens covered most 

 of the pieces astray on the dunes. Similar records have been made in 

 Epping Forest by Paulson and Thompson 4 who found Cladonia fimbriata 

 var. tubaeformis and Lecidea granulosa growing on an old boot. These 

 authors connect the sodden condition of the leather with its attraction for 

 lichens. 



On pasteboard Even on such a transient substance as this Lesdain 



found a number of forms, most of them, however, but poorly developed : 



Cladonia furcata (thallus), Parmelia subaurifera (beginning), Xanthoria 



parietina (beginning), Physcia obscura, Placodium citrinum (thallus), PI. 



1 Richard 1877. 2 Darbishire 1909. 3 Cf. p. 234. 4 Paulson and Thompson 1913. 



