Tilden: pilinia and stigeoclonium. 603 



History of the genus Pilinia. Upon a comparison of the 

 literature the greatest diversity of opinion concerning the 

 nature of the genus Pilinia, was found to prevail, and, indeed, 

 according to some authors no such genus should be maintained. 



The genus was created in 1843 by Kuetzing (I), and in it he 

 placed the species P. rimosa. His specimens were gathered 

 near Cuxhaven, in July, 1839. 



The earliest description at hand is that of Rabenhorst (I), 

 published in 1868. "Pilinia Ktz. (1843): Fila articulata erecta, 

 simplicia vel parce ramosa, basi callosa quasi radicata affixa, 

 in stratum crustaceum tenue spongiosum olivascens coales- 

 centia. Propagatio ignota. 



"P. rimosa Ktz. (Phycol. gener. p. 273,) P. lignicola, Crus- 

 tacea,' olivaceo-viridis, initio porosa, postea rimosa, mucosa; 

 filis ramisque fasciculatis; articulis diametro (0.00029-0.00038") 

 aequalibus vel duplo longioribus. v. v. 



' 'Hab. in postibus lignisque aestu maris cohtinuo irroratis in- 

 sulae Suelt, Norderney (L. R), prope Cuxhaven, ubi frustra 

 quaesivi, detexit 1839 mense J olio cl. Kuetzing." 



Dr. Wood (I) was the next contributor to the genus. He, 

 rather hesitatingly, however, offers a new species. The de- 

 scription is as follows: 



"Genus Pilinia Ktz. Filaments articulate, erect, dichoto- 

 mously branched, fixed by the base, aggregated into a some- 

 what spongy fragile crustaceous stratum. Method of propa- 

 gation unknown. 



Pilinia diluta Wood (sp. nov.) Growing on stones and 

 rocks, forming a grayish-green stratum; filaments and branches 

 fasciculate, with the apices obtuse; joints H- 3£ times longer 

 than broad. Diam. Max. 0.0004". Hab. In a large fountain, 

 near Belief onte, Centre county, Pennsylvania; Wood." 



No more attention was paid to the genus until 1888, when De- 

 Toni ( I ) in comparing the genera of the Trentepohliaceae, 

 notes that the genus Pilinia Kuetz. seems to him identical with 

 the genus Acroblaste Reinsch (Relnsch I). A year later he 

 makes a more extended exposition of this belief (De-Tonl II) 

 and quotes Hansgirg ( II ) as agreeing with him on this point 

 and also referring Chaetophora pellicula Kjellm. (Kjellman I) 

 to the same genus. Accordingly in his Sylloge Algarum {De-Tonl 

 III) he places both Acroblaste and Chaetophora pellicula under 

 Pilinia rimosa. 



Wille (I) holds a different view, he retains Acroblaste as an 

 authentic genus, but removes Pilinia to the "unsichere gat- 



