Vol. n Reed. — Two New Ascomycetous Fungi. 155 



There is not the least donbt that the algal portion of this 

 Alaskan composite is a Prasiola, but of just what species it is 

 rather difficult to determine as I have access to but few authentic 

 specimens, and most of the descriptions and figures are inadequate 

 and unsatisfactory. Both the habit of the composite and its 

 association with the fungus suggest Masfodia iessellata Hooker, 

 but Hooker's figures appear to be diagrammatic, while his 

 description does not agree with our Alaskan specimen. Hariot, 

 however, collected the same ^^ Prasiola tessellaia " on the Island of 

 Terra Del Fuego, and carefully describes it in his article on the 

 algfB of the "Mission Scientifique du Cap Horn's" (1882-83). 

 He carefully describes and figures the microscopic structure, and 

 compares his material with Hooker's specimens, finding them to 

 be identical, though his specimens were marine and Hooker's 

 were fresh water. Hariot discovered the composite nature of the 

 Mastodia, which Hooker never suspected, and decided that it was 

 Prasiola tessellaia associated with an ascomycetous fungus, 

 Liesiadia Prasiohe Winter. Since Hooker's first publication of 

 Mastodia tessellaia in the Journal of Botany (1845) it has been 

 republished, figured, and described by several botanists, yet 

 Hariot is the only one who really makes the nature of the 

 composite clear. In 1849, Kiitzing referred Mastodia iessellata. 

 Hook, to the genus Prasiola. He gives a figure in Tabula 

 Phycologicffi (Cf. Vol. 5, PI. 40), which, according to Hariot, 

 resembles the plant described by Hooker and Harvey. Rab- 

 enhorst in 1868 (Fl. Europ. Alg. Ill, p. 311) reproduces 

 Kiitzing' s figures and descriptions, but does not mention the 

 conceptacles which characterize it, or make any comment upon 

 the nature of the plant. J. G. Agardh also discusses the 

 " Viva tessellaia " of Hooker and Harvey, and the Prasiola 

 iessellata of Kiitzing, and decides that they are synonymous; 

 but at the same time he considers Mastodia to be a dis- 

 tinct genus. Bornet likewise studied Hooker's Mastodia and 

 decided that it was a composite consisting of a Prasiola and 

 an ascomycetous fungus. With all these discussions of the 

 Mastodia and Prasiola iessellata, there is no description of 

 the Prasiola any better than Hooker's; hence the difficulty of 

 comparing the Prasiola of the Alaskan composite. The Alaskan 



