Spiloma.] I.1CHENES. 165 



the extreme minuteness of the parts prevent its being detected; 

 and which, in one individual (S. gregarium) actually rises above 

 the surface of the thallus, and is often found quite bare, forming 

 what appears a very conspicuous apoihecium" 



1. S. microsedpicum, Turn, and Borr. (microscopic Spiloma); 

 crust spreading widely filmy very thin greyish, apothecia ex- 

 tremely minute black lead-coloured when dry. Turn, and Borr. 

 Lick. Br. p. 30. E. Bot. t. 2396. 



Common on boarded buildings, &c — " Thallus or crust a most obscure 

 grey film, spreading indeterminately and very widely, so thin as merely 

 to tinge the fibres of the wood on which it grows. Apothecia, (or pul- 

 vinuli, as they are called by Messrs. Turner and Borrer,) not discernible, 

 except with a microscope of considerable power. Sporules bluish when 

 dry, black when wet, readily adhering to the fingers." 



2. S. murdle, Turn, and Borr. (wall Spiloma); crust none ? 

 apothecia extremely minute confluent black. Turn, and Borr. 

 Lick. Br. p.3\. E. Bot. 1 2397. 



On plastered walls of cottages, in the parishes of Hurst-pierpoint and 

 Albourne, Sussex; and on the walls of Burgh Church, Suffolk.— The 

 absence of thallus is accounted for by the authors of Lichenographia Br. 

 by the circumstance of this plant having as yet been detected only on 

 mortar and coarse-grained stone, on which substances the thallus of other 

 Lichens is known to grow very thin and sometimes altogether to dis- 

 appear. 



3. S. splmrdle, Ach. (globose parasitic Spiloma); parasitic, 

 apothecia minute subglobose scabrous black opaque. Ach. Syn. 

 p. 2. 



Upon the crust and podctia of Isidium coralhnum and other Lichens. 

 —This is enumerated in Mr. Borrer's list of the British species; but 

 1 am unacquainted with it. 



4. S. dispcrsum, Turn, and Borr. (dispersed Spiloma); crust 

 filmy very thin greyish, apothecia mostly dispersed hemisphe- 

 rical sooty-black internal lv of a yellowish-green. Turn, and 

 Borr. Lick Br. p. 32. E. Bot. t.2398. 



On old rails, not unfrequetot. — This agrees with 8. microscopic*** in 

 its obscure filmy thallus, but differs abundantly in the Bize, disposition 

 and structure of the apothecia. "It is nol unfrequently found inter- 

 mixed with it; insomuch that we would by no means be understood S3 

 speaking with certainty, when we mention its thallus, whether this thal- 

 lus may not, in reality, belong to the other, and S. ditpmum be alto* 

 gether destitute of one." 



5. S. minitinu. Sin. (golden Spiloma); crust inclining to tar- 



tareous thin white, apotheeia rather eon\.\ al Length eontlueiit 



deep brown internally yellow. E. Bot. t. 2078. Turn, and 



Borr. Licit. Hi. />. •')•'*. S. tricolor. Ach. Sun. p. 'J. 



Common on timber, in old walls, ftc, Busses ; on Elm-bark ; t Port- 

 slade: on the church-walls at Henfield, Sussex* and Wrentham, Suf- 

 folk; and eery line mi ehurehes near Bur\ St. KdinumU. — OfUlisvety 



curious and beautiful species, the apothecia are M about the sise ol 

 poppy-seed, round, more or less convex, soon becoming confluent ami 



