206 THE JOTTIl>'AL OF BOTANY 



P. obsctira var. virrlla (Ach.) Th. Fr. lias a rather infrequent 

 form fa rescens Cromb. {^. Hue ia?ia Kurm.). The medulla gives a 

 purplish reaction owing to the intimate association of the plant with 

 Xanthorin jmrietina. When the plant grows with Parmelia fnligi- 

 nosa, the medulla of another state may give a reddish colouration with 

 chloride of lime. 



Placodinm elerjans var. tenuis Wahl. Bwlch Gwyn (50). 

 P. nuirorum (Hoffm.) D. C. Taunton and Chard (5), Bleadonand 

 Bruton (6). 



P. aiirantium (Pers.) = P. caUopismum (Ach.) Merat. The type 

 is not common. Orchard Portman and Quantoxhead (5), Brean 

 Down, Shapwick and Hii^h Ham (6), Burton Bradstock (8), Koss 

 (3(5). — Var. plicaium (Wedd.) is the common plant which is often 

 called Lecanora sympageum, a name to whioli it has no right, Lichen 

 sympageus Ach. being merely a colour form of the type. Hue's name 

 for this plant is L. Ileppiana. 



P. microihaUinum (Wedd.) Oliv. is a plant very similar to 

 P. Johulatum (Somm.) Hepp. There seems to be no real distinction 

 between the two excei)t that the former grows on Verrucaria maura : 

 this habitat is common for plants named P. lohulatum by British 

 lichenologists. 



Sqitaman'a suhcircinata (Nyl.) OUv. On sarsen stone, Staple 

 Fitz))aine (o). 



hiphrafora cand leans (Dicks.) Jatta. Chai-d and Taunton dis- 

 tricts (5), Mendip (6), Symond's Yat (34), Backbury Camp (36), 

 Ingleton (65). L. candicans Schaer. because of its uniseptate spores 

 is excluded from Placodinm or Pyrenodesmia. The mdiately-lobed 

 thallus separates the genus Dipliratora from Leconia. 

 Candelaria concolor (Dicks.) Arn. = i. laciniosa Nyl. 

 Callopis)na epixanthum (Ach.) A. L. Sm. Taunton (5), Shap- 

 wick (6). 



C. citrimim (Hoffm.) Koerb. is usually on mortar, but often 

 spreads out over the surrounding rock and occasionally over soil or 

 decaying moss. 



C. erythreUum form. nov. ecrustaceum. Apothecia and spores as 

 in the type, but the thallus is absent or scarcely visible. It forms 

 extensive ])atches on the White Lias cliff at East Quantoxhead (5). 

 Miss A. L. Smith kindly tested this plant. 



C. cerinum form cyannleprum (D. C). On pale, High Ham (6) 

 and Orchard Portman (5). 



C. hcEmaiites (Charb.i. On tree, Buckden (64, T. Hebden). 

 C. pyraceum (Ach.) Arn. Winsham and Aisholt (5), Koad (6). — 

 Var. pyrithoma (Ach.). Merridge near Bridgwater (5). 



C. viteUinulum (Nyl.) Arn. Torquay (3), Cheddon and Corfe 

 (5), Shapwick (6). 



Lfirropiaca xantholyia Nyl. On dolomitic conglomerate, Ship- 

 ham (6). 



Lecanora (jaJaciiaa var. dispersa ( Pers.) Ach. and var. dissipafa 

 (Nyl.) B. de Lesd. Taunton (o). — Var. tirhana (Nyl.) Harm. 

 Cheddon Fit/,])aine and Kingston (5). 



i. suhfusca. In this group Crombie, following Ny lander, attached 



