54 



adhere in their whole length; no unbroken 



basal layer U. consociata f. typica 



2. Filaments often kneed at intervals, coalescent 

 only at the base, forming an unbroken basal 



layer U. consociata var. islandica 



B. Ghromatophore thickened in the middle. . U. subflaccida 



97. I. flacca (Dillw.) Thur., K. Rosenv. Grl. Havalg. p. 936, 

 Deux. Mém. p. 115; Wille, Studien p. 18. 



This species has been so exhaustively described byRosen- 

 vinge (Grl. Havalg. I.e.) and Wille (I.e.) that I have nothing 

 to add. 



The filaments usually contain 2—3 pyrenoids in each cell, 

 but cells with one, or, in the thicker filaments with four pyre- 

 noids are not rare. The number of pyrenoids seems to be 

 dependent on the size of the cell, that is, larger cells contain 

 more pyrenoids than smaller ones, as pointed out by Wille 

 (1. с. p. 20). 



The American Ü. flacca, as it is figured and described by 

 Hazen (Am. Ulothricaceæ p. 155, pi. 20, fig. 7 — 9), cannot in 

 my opinion be regarded as identic with the Greenlandic and 

 North European species. Ü. flacca Hazen is 10 — 25 /u thick 

 and contains only one pyrenoid in each cell, it is moreover 

 most likely without rhizoids, as the rhizoids are neither figured 

 nor mentioned in the description. The Greenlandic species is 

 14 — 80 fj. thick, contains 1: — 4 pyrenoids in each cell, and has 

 rhizoids. Ha zens species seems to be nearly related to Ü. 

 pseudoflacca Wille and the two species are thus most naturally 

 regarded as identic by Hazen (Am. Ulothricaceæ p. 156); but 

 Ü. pseudoflacca Wille is so different from the species named 

 U. flacca from Greenland, Iceland, the Færoes and Norway, 

 that any confounding of the two species seems to be excluded, 

 while specimens of U. pseudoflacca from Greenland have been 

 determined as U. itnplexa Kiitz. 



As to the distribution of the species in West Greenland 



