ACOTYLEDONS. LICHENS. Thdotrema. 45 



HAB. On rocks with the preceding, Lightf. Common. 



Sir James Smith justly remarks, that this seems to unite the foregoing 

 and the following species. 



7. E. Weleri) thallus cartilagineo-coriaceous lobed greenish 

 brown olivaceous beneath rather tawny or blackish on both 

 sides smooth, the lobes laciniated waved plaited and crisped 

 crowded, orifices rather convex black. Ach. Syn. Lick. p. 103. 

 Lichen aquations, E. B. t. 594. 



HAB. Rocks and stones over which wafer trickles,, within reach of the 

 spray of cascades, &c., not uncommon. 



Div. II. CCENOTHALAMI. Lichens whose apothecia are form- 

 ed in part from the sulstance of the crust or thallus. 



SECT. I. PHYMATOIDEI. Apothecia included in wart-like pro- 

 cesses which are formed of the thallus. 



11. PORINA. 



Universal receptacle crustaceo-cartilaginous, expanded, plane, 

 adnate, uniform, with wart-like processes. Partial receptacle 

 immarginate (1 or more), hid within the substance of the 

 wart, and surrounded by a very thin diaphanous membrane, 

 its orifice thicker coloured, in the surface of the wart, and 

 containing a subglobose cellular nucleus. 



1. P. pertusa, crust smooth even whitish grey, warts of the 

 apothecia subglobose, orifices many depressed black. Ach* 

 Syn. Lich. p. 109. Lichen pertusus, Lightf. p. 802. E. B. 

 t. 677. 



HAB. Trunks of trees and sometimes rocks, Lightf. 



12. THELOTREMA. 



Universal receptacle cnistnceO'CaTtilagiuous, spreading, plane, ad- 

 nate, uniform, with wart-like processes, perforated with a wide 

 pore, and margined. Partial receptacle solitary, included 

 in the wart, with a double coat; one dimidiate, superior, 

 thick (black), rarely wanting ; the other very thin, membra- 

 nous, sometimes breaking above, inclosing a compressed cel- 

 lular nucleus placed in the bottom of the wart. 



1. Th. lepadinum, crust smooth whitish, warts of the apothecia 

 smooth somewhat cone-shaped with the margin of the aper- 

 ture thin simple somewhat inflexed and contracted covered at 

 the bottom with a membrane which bursts. Ach. Syn. Lich. 

 p. 1 15. Lichen inclusus, E. B. t. 678. 



HAB. On the bark of Ilex aquifolia, at Bilston-burn, near Edinb., 

 Mr. G. Don. 



2. Th. exanthcmaticum, crust subtartareous thin contiguous 



