186 LICHENES. [Lecanora. 



convex without a border. Sm — Patellaria ulmicola, DC— 

 Lecidea luteo-alba, Ach. Syn. p. 49. — Lichen luteo-albus, Turn, 

 in Linn. Trans, v. 7. p. 92. t. S.f. 3. E. Bot. t. 1426. 

 On the bark of trees, in various parts of England. 



67. L. aurantiaca, Ach. (saffron-coloured Lecidea); crust 

 granulated whitish-lemon-coloured, apothecia sessile rather 

 convex orange- coloured with a yellow waved border. Sm — 



Ach. Syn, p. 50 Lichen aurantiacus, Light/. — Lichen sali- 



cinus, Schrad E. Bot. t. 1305. — Lecanora salicina, Ach. Syn. 



p. 175. 



On the trunks of trees, especially of Willow and Poplar.— Mr. Borrer 

 has determined this to be the Lichen aurantiacus of Lightfoot, whose 

 older appellation I consequently prefer. 



68. L. erythrella, Borr. Mss. {orange Stone Lecidea); crust 

 lemon-coloured thin dispersed in minute angular smooth frag- 

 ments, apothecia sessile deep orange with a lighter border at 

 length .becoming nearly globose and the border obliterated. Sm. 

 — Lecanora erythrella, Ach. Syn. p. 175. — Lichen erythrellus, E. 

 Bot. t. 1993. 



On rocks and stone-walls : not unfrequent in the Highlands of Scot- 

 land. — Mr. Borrer thinks it is scarcely distinct from the preceding. 



14. Lecanora. Ach. Lecanora. 



Thallus crustaceous, spreading, plane, adnate, uniform. Apo- 

 thecia (patellulcc) orbicular, thick, sessile and adnate, the disk 

 plano-convex, its border thickish, formed of the crust and of the 

 same colour. — Name ; Xzkxhcv, a small shield, and wga, form ; 

 from the form of the apothecia. — Our valued and learned friend, 

 Mr. Borrer, says he adopts the Genus Lecanora with reluctance, 

 as distinguished by an unsatisfactory character from Parmelia. But 

 surely inhabit should be considered together with the structure of 

 the thallus or frond (and without it our arrangement of Crypto- 

 gamiae, in particular, would be most incongruous,) the greater 

 number of the Acharian Lecanora with their crustaceous fronds 

 and the almost leafy or coriaceous Parmelice ought to be separ- 

 ated. Still I must agree with that eminent Lichenist, that the 

 limits of this, as of almost all the Genera of Lichens, are not 

 easily defined. There are connecting links, and the place of 

 such must perhaps ever remain doubtful. 



* Apothecia black or dark brown, sometimes pruinose. 



1. L. dtra, Ach. (black-shielded Lecanora); crust subdeter- 

 minate rugged slightly cracked granulated and white, apothecia 

 nearly flat deep-black the border elevated white at length 



notched and flexuose Ach. Syn. p. 146. — Lichen ater, E. Bot. 



t. 949. 



Common on walls and rocks. 



2. L. argopholis, Ach. (white-scaled Lecanora); crust smooth 

 rugged and wartecl pale the warts at length imbricated some- 



