GENERAL CHARACTERS OF BRITISH LICHENS. 61 



thallus, in which case it is of similar colour therewith ; and 

 proper when it possesses a dissimilar structure and colour, 

 as in Lecidea and Calicium. Each exciple usually contains 

 a single thalamium, but sometimes two or three are aggre- 

 gated together, both in Angiocarpous and Gymnocarpous 

 species, forming confluent or symphycarpous apothecia, as 

 in some Cladonice. In form the apothecium is usually 

 round ; sometimes it is linear, elongated, or irregular. It 

 is said to be scutellate [scutella, a platter) when round, 

 flattened, or plate-shaped with a thalline exciple, as in Par- 

 melia and Lecanora ; peltate (pelta, a buckler or target) 

 w T hen of similar form, but destitute of a distinct exciple, 

 as in JJsnea, Cetraria, and Peltigera ; patellate {patella, a 

 shield) when round, convex, or semi-globular, with a proper 

 exciple, as in Lecidea and Calicium ; capitulate (capilulum, 

 a head) when irregularly round, globular, and seated on the 

 apex of a stem- like prolongation from, or form of, the thal- 

 lus, as in Cladonia, Stereocaulon, and B&ornyces ; lirellate 

 {lirella, a furrow) when linear, or elongated in the form of 

 a chink or furrow, frequently irregularly divergent or stellate, 

 with a proper exciple, as in the Graphidem ; and verrucous 

 [verruca, a wart) when globular or wart-like, seated directly 

 on or partially in the thalline surface, the exciple being a 



