92 Mr, Turner's Descriptions of 
3. Lichen luteo-albus. 
L. crusta leprosa tenuissima alba ; scutellis vitellinis ; junioribus 
planiusculis, adultioribus tuberculiformibus. 
Tab. VIII. Fig. 3. 
Habitat in cortice arborum; prope Croydon, D. Dickson: in 
insula Mona, D. Davies : in comitatu Durham, D. Harri- 
man : apud Acle et Coltishall in Norfolcia. 
Crusta leprosa, tenuissima, alba, nitida, ab arborum, quibus in- 
nascitur, truncis vix nisi colore dignosci potest. Hanc fere ob- 
tegunt scutellae, ambitu subrotundae, numerosissimae, confertae, 
magnitudine papaveris seminum, initio planiusculae, vel levis- 
sime concavae, margine tenuissimo, et si per lentem attente ob- 
serventur, pallidiore cinctae ; progrediente aetate, tuberculorum 
formam aemulantes, et saepe, dum madent, subglobosae. Sic- 
catae fiunt compressae. Color his plerumque vitellinus inter- 
dum aliquantulum virescit. 
Among the crustaceous Lichens scarcely any subdivision is at- 
tended with more difficulty than that with yellow shields; for 
what some authors have considered as varieties of Lichen can- 
delarius*, and others have regarded as distinct species, are so nu- 
merous, and occur in so many different forms, that this single 
circumstance has given rise to an infinity of perplexity. It is 
not, therefore, without the greatest diffidence that I now hazard 
* In speaking of L. candelarius, I think it necessary to observe, that I do not intend 
the plant so called by Dr. Acharius, but that which Professor Hoffman has figured in 
his Plantce Lichenosce under the name of L. vitellinus, and which by Mr. Dickson and 
most other botanists is considered the true L, candelarius, 
the 
