OF ARTS AND SCIENCES : APRIL 12, 1864. 283 



sporidia ") which he had in view, as occurring commonly on tropical 

 barks, was the well-known flat state ofL.parasema, Ach. (L. disciformis, 

 Nyl.), which really is common on such barks, and not what is now called 

 L. enteroleuca. And this amounts to a determination of L. parasema as 

 that part only of the original species which is characterized by bilocular, 

 finally brown spores : a limitation dating at least from 1837, if not from 

 1824. "X. disciformis, Fr.," cited as a synonyme in Moug. & Nestl. 

 Crypt. Vog. n. 745, has no other authority for its definition, that I am 

 aware of, than the specimens published by the French botanists in con- 

 nection with it, and in my copy at least this definition is uncertain, as 

 one of the three specimens (with a similar hypothallus to that of the 

 other two, only here more evidently conditioning the thin thallus, and 

 smaller, flat, dark-reddish apothecia) has the ovoid, simple spores 

 characterizing L. enteroleuca. L. parasema being as common as it is 

 in the warmer regions of the earth, and doubtless passing there into 

 states (the varieties ccesio-pruinosa, and cerugmascens, Nyl., and e7i- 

 dococcina (th. intus miniato), mihi, are some of these) unknown else- 

 where, and L. myriocarpa (DC), Nyl., also occurring in those regions, 

 I do not venture at present to distinguish further, by a diagnosis, the 

 L. catasema of Lich. Cub. n. 242 ; but the apparently granulose thallus 

 of this lichen seems to differ from the granulate conditions of L. 

 parasema, while the minute, soon proliferous apothecia (the thalamium 

 in which, brownish in a thin section, is made up of conglutinate 

 paraphyses, — contrasting both with L. parasema and L. myriocarpa 

 the almost colorless thalamium of which consists of loosely coherent, 

 fihform paraphyses), and especially the small spores, which are less than 

 those of the last-named species (Fr. Lich. Suec. n. 353 ; Nyl. in 

 Lindig. Lich. N. Gran. n. 742) and rather resemble the spores of some 

 Trachylia, may well make proper a separate notice of it. There are, 

 in Mr. Wright's collection, some small forms on living bark, approach- 

 ing the other. 



Lecanactis, Eschw. Syst. p. 14 (founded on Lichen lynceus, E. 

 Bot., which Acharius referred first to Lecidea and then to Arthonia) 

 was accepted by Fries (Lichenogr. p. 374) in a diiferent. sense from 

 what it afterwards assumed in the mind of its author, and has been 

 since illustrated and extended by Koerber (Syst. p. 275). The group 

 touches at once on Lecideaceous and Graphidaceous types, and its im- 

 portance in the system appears tolerably evident if the close natural 

 affinity of L. lyncea (an Opegrapha, according to Borrer, Schserer, and 



