144 Mr* Turner's Descriptions of Eight New British Lichens. 



Alga arborea, irregulariter orbicularis, diametro bi-tri-polli- 

 caris, interdum semipedalis. 



Crusta ambitu obsolete zonato-limitata, membranacea, tenuis- 

 sima, laevis, in stirpe adultiore centrum versus crassior, sub- 

 verrucosa, et leviter rugosa. 



Scutellce ita copiosae ut non raro crustam fere totam occupant, 

 congestae, exigua3, et papaveris semine vix majores, orbiculares, 

 sed mutua pressione interdum angulosae, margine crustee conco- 

 lore, crassiusculo, integerrimo, vix, aut ne vix, elevato, disco 

 semper piano, membrana tenuissima, ejusdem qua margo sub- 

 stantias, et quasi ab illo ort&, obtecto, unde stirpi Lecidece fades, 

 intus pulchre flavicante. 



Color crustae albus, glaucescentia tinctus, sine nitore, in planta 

 sicca et madefacta idem. 



Substantia e membranaceo tartarea. 



The scutellae in this Lichen are very remarkable, the mem- 

 brane that covers the disk being to all appearance of the same 

 substance as the margin, and a continuation of it, so that they 

 have altogether the look of the patellulce of a Lecidea. The edge 

 of the crust is not composed of minute parallel fibres, as in 

 Lecidea atro-flava and many of the species growing on stone, but 

 rather resembles that of some Variolarice or of Isidium coccodes, 

 being extremely thin, silky, and obsoletely zoned. The situa- 

 tion of Parmelia velata is between P. albclla and parella, to the 

 latter of which it is by far most nearly allied, indeed so nearly, 

 that, though I have the sanction of Dr. Acharius and Mr. Borrer 

 for thinking them distinct, and though I have myself gathered 

 them in plenty in Sussex, without perceiving any immediate gra- 

 dation, I would not be understood as speaking without much 

 diffidence upon the subject. P. velata is distinguishable from 



P. albella 



