Z ANGIOCARPOUS LICHENS. 



nor describes their form and number, so as to render 

 them available in the discrimination of genera or species.* 

 They were also previously known to Hedwig, (see his 

 Theoria, p. 206, 1798,) in tab. xxxiii., figs. 3, 4, 5, 6, 

 of which work he figures the sporidia of three different 

 Lichens; and still earlier to Dillenius (Hist. Muse, 

 1741, p. 75,) and Micheh, (Nova. Plant. Genera, 1729, 

 p. 73, & tab. xxxvi., lii.) The only writers, however, who 

 have devoted anything like attention to the subject are 

 Eschweiler and Fee. Eschweiler, in his 'Syst. Lichenum,' 

 (Norimb., 1824, 4to,) has one plate in which he figures 

 the sporidia of the genera of crustaceous Lichens, and 

 mentions also their forms in his generic characters ; and 

 in his labours in the splendid ' Icones Plant. Crypt. 

 Brasil.,' by Martins, (Monachii, 1828, fol.) he figures the 

 sporidia genus by genus, but according to Fee incorrectly. 

 Fee, in his *Essai sur les Cryptogames des Ecorces 

 Officinales,' (pt. ii, 1837,) has five 4to plates filled with 

 minute figures of sporidia, and applies them to the dis- 

 tinction and confirmation of the characters of the genera 

 into which he proposes to arrange Lichens. His labours 

 being limited to the Lichens found on the barks of 

 foreign trees used for medicinal purposes, necessarily 

 include but very few of our British species. It is believed 

 that the present is the first work which has been hitherto 

 devoted to the examination of the sporidia of British 

 Lichens. 



To make the forms of the sporidia characteristic of 

 genera, except in a very few instances, would, it is con- 

 ceived, lead to an almost endless subdivision, if fully 

 carried out. Their real value rather seems to be as a 

 distinguishing and confirmatory specific character. And 

 how truly valuable a character they afford in the accu- 

 rate discrimination of species, the following pages and 

 plates vrill repeatedly and abundantly testify; and also 



* He also mentions tlie ultimate spores contained in the sporidia, under 

 the term Qongyli. 



