CRYPTOGAMIA LICHENES. 101 



that they look as if they had been smoked, or rubbed over 

 with gunpowder. 



59. ARTHONIA. 



1. A. astroidea, crust thin, even, white or greyish-white ; apo- 

 thecia black, numerous, even with the crust, rounded, more or 

 less stellate HOOK. Scot. ii. 36. 



Hob. On the bark of the ash and elm, occasionally. 



2. A. swartziana, crust thin, even, greyish-white; apothecia 

 black, even with the crust, numerous, short, somewhat linear, ir- 

 regularly branched ACH. Syn. Lick. 5. 



Hob. On the ash, near the Retreat, Berwickshire. 



When I mention that the names to my specimens were at- 

 tached by Mr ARNOTT, I need scarcely add that no doubt 

 can be entertained of the correctness of their application. 

 I have described them without reference to the descrip- 

 tions of others, and to me the species appear too nearly 

 related. 



60. SPILOMA. 



1. S. tumidulum, crust very thin, even, greyish-brown; apo- 

 thecia tile-red, irregularly oblong, crowded, rough or granular 

 HOOK. Scot. ii. 35. 



Hob. On the bark of trees. On the hazel in the dean at 

 the Pease-bridge. 



61. VARIOLARIA. 



1. V. amara, crust rugose, cracked, uneven, subpulverulent, 

 white or greyish ; warts of the apothecia appressed, plano-concave, 

 margined, bearing soridia of the same colour as the crust.- 

 HOOK. Scot. ii. 46. Lichen fagineus, LIGHTF. Scot. 807. WITH. 

 iv. 4. 



Hob. On the bark of the ash, birch, and oak, not uncom- 

 mon. 



The crust of this lichen is intensely bitter, and it imparts 

 this bitterness readily both to water and alcohol. BRA- 



