10 THE DETERMINATTOX OF LICHEXS IX THE FIELD 



Concoloi'ous or almost so on both sides, often 



spiny at margin. Sp. colourless, simple... Cetraria (/). 

 1J<. On tidal rocks. Th. dicliotomously branched 



like a small Fucios, with Stigonema algie . Lichina. 



Not on tidal rocks and plant not f ucoid l.j. 



15. Thalline lobes or cylinders much branched 

 with uneven or nodulose surface. Algal 



cells not JS'ostoG (j) IG. 



Little branched, the surface usually even (k). 18. 

 IG. Thaliine cylinders cellular, alga Scytoiiema. 



Ap. sessile Polychidium. 



Not or vaguely cellular, alga ^ticfonema. 



Ap. innate 17. 



17. Branchlets spiny. Paraphyses distinct. Sp. 



simple, colourless Ephebeia. 



Branchlets not spiny. Paraphyses none. 



Sp. 1-septate, colourless Ephebe. 



18. Th. with cellular cortex 19. 



Th. without cellular cortex. Tubes swollen 



at apices 20. 



19. Algal cells mostlj'- bright green. Ap. in 



thalline pits Solorina spongiosa (/). 



Algal cells blue-green i^Nostoc). Ap. not 



sunk in th. pits Leptogium. 



20. Algal cells Nostoc, in chains. Thalline sec- 



tion red with iodine. Sp. septate 21. 



Algal cells Scytonema or Glceocapsa (m). 



Sp. simple .-. 22. 



21. On trees in upland districts. Th. section 



blood-red with iodine. Sp. 1-3-septate, 



4-5 times as long as broad Synechoblastus fascicularis. 



On mossy rocks in alpine places. Th. section 

 wine-red with iodine. Sp. muriform, less 

 than twice as long as broad CoUema ceraniscum. 



22. On decayed mosses on alpine rocks. Algal 



cells Scytonema Schizoma lichinodeum. 



On rocks, usu. in little tufts on calcareous 



rocks. Algal cells Glceocapsa Synalissa. 



23. Th. t gelatinous; filaments or lobes prostrate 



or erect. Algal cells blue-green (;i) 25. 



Th. not gelatinous, of interlacing and pros- 

 trate filaments. Algal cells i]ot blue-green. 24. 



24. Th. with filaments itconstricted. Hyphse 



much twisted. Algal cells reddish ( Trenie- 



pohlia) Coenogonium. 



Th. with filaments little constricted. Hyphae 

 little twisted. Algal cells green {Clado- 

 2)hora) Racodium. 



25. Th. of tangled filaments. Algal cells Sci/fo- 



uema OY Stif/onema 26. 



Th. of -+-ereet lobes. Algal cells 3^o6'/oc ... 28. 



