286 



POPULAR HISTORY OF LICHENS. 



pers, without any regard to system." Dr. Greville, a very 

 high authority, includes them in his ' Algse Britannicse/ but 

 expressly states, "in regard to habit, the Lic/iina touch 

 closely on the boundary of the Lichens." Harvey, in his 

 classic work on British Algse, however, excludes this genus, 

 thereby distinctly implying his belief that it does not pro- 

 perly pertain to the Algse. In the structure of the thai! us, 

 as well as in the characters of the apothecia and spermo- 

 gones, the LicTiincB are decidedly lichenoid. In the charac- 

 ters of their apothecia and contents they resemble the genera 

 Calicium and Spk^eropkoron. The fructification is angiocar- 

 pous ; the spores are glued to each other in linear series, and 

 assume their mature form only after dissociation and escape 

 from the thecse, but they do not accumulate on the surface 

 of the thalamium as in these genera. The spermogones in 

 L. pygrncea occur immediately below the spherical apothecia 

 which terminate the thalline ramules ; their ostioles are easily 

 recognized, and their cavity is pericellular. The spermatia 

 are very minute and numerous, ovoid, and generated acro- 

 genously from irregular cylindrical sterigmata. In L. con- 

 finis the spermogones are small ovoid bodies, seated on the 

 extremities of the thalline ramuscules, and frequently im- 

 planted upon the apothecia themselves. The spermatia are 



