24 THE DETERMITiATIOX OF LTCHEJs'S IX THE FIELD 



8. Th. reddish or ferruginous 9. 



Th. yellow (often somewhat greenish) 10. 



9. Th. with a blue or violet coloration with 1. 



(Also forms of Lecidea confliiens and 



Aspicilia cinereorufescens.^ Rhizocarpon cederi. 



Th. without a blue or violet coloration 

 with I. (Also forms of Lecidea contigua, 

 L. Iitli02)lnla, Biatorina lentictdaris, 

 Asjyicilia Jacustris, and Acarosjyora rti- 

 fescens.) Lecidea dicksonii. 



10. Th. a citrine-yellow powdery crust on mortar 



and surrounding rock, K+ purplish, C — 



I_ Callopisma citrinum. 



Th. yellow, on trees, rocks, etc., K4- purplish 



or crimson C — I— H- 



T]i. without a purplish or crimson colora- 

 tion with K ; 12. 



11. Th. ochraceous-yellow, at first yellow with K 



and then crimson. Rare plant on rocks... Lecidea armeniaca. 

 Th. immediately purplish or crimson Avith K. 



On rocks, trees, etc Callopisma. 



12. Th. of a sulphur-coloured or greenish-yellow 



powder, K— C- I — . Algal cells oblong 

 and unnucleated. On ground, decayed 

 vegetation, or dead wood (rarely on rocks). 



Coniocybe furfuracea (i). 

 Algal cells nucleated and globular 13. 



13. Th. bright yellow, K-C- ; medulla blue 



with I. Hvpothallus black. On rocks. 



Rhizocarpon geographicuni. 

 No reaction with I 1^- 



14. Th. having a reddish reaction with C. On 



trees and pales l^'^- 



Th. having a reddish reaction with C. On 



rocks 1^>- 



Th. without a colour reaction with C 17. 



15. Th. greenish or dark verdigris-green. (Also 



some varieties of L. jmrasema. ) Lecidea flexuosa. 



Th. sulphur-coloured to greenish-vellow, usu. 



pulverulent and effuse ."^ Lecanora expallens (c). 



16. Th. sulphur-coloured, thickish, verrucose, 



oft«n ±sorediate, K -\- vellow Lecidea protrusa (d). 



Th. yellowish-green, smoothish, K- ... Buellia verruculosa (e). 



17. Th. without a colour-reaction with K. On 



rocks 1^- 



Th. without a colour-reaction Avith K. On 



trees 1^^- 



Th. with a yellow (sometimes turning red) 



reaction with K 20. 



18. Th. of small egg-yellow granules Candelariella vitellina. 



