478 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



coarser plants with Dasyoid or Cliftonioid rather than Polysi- 

 phonioid habit, and the origin and arrangement of the branchlets 

 and monosiphonous filaments are more or less different in all of 

 these. In its delicate Polysiphonioid habit, S. filamentosa is nearer 

 the group which includes S. miniata (Ag.) J. Ag. (the type of 

 which we have seen in Herb. Agardh), S. intermedia Grunow, 

 and S. mutabilis (Harv.) J. Ag., but these differ not only in ab- 

 sence of monosiphonous filaments, but also in cortex characters, 

 etc.; in S. mutabilis^ also, the branches have a marginal or sub- 

 marginal instead of mid-central origin. 



The apparent incongruity of referring delicate plants of the 

 miniata type to a genus originally based upon the fleshy mem- 

 branous Sarcomenia delesserioides has already been remarked 

 by Grunow and discussed at length by J. Agardh. In placing 

 the above-described new species in Sarcomenia^ we accept, for 

 the present, the current conception of the limits of the genus". 



This shows that Howe had some doubts when he referred 

 his plant to this genus which already has so many different com- 

 ponents making it yet more heterogeneous. A division of it seems 

 therefore rather desirable, a beginning being now made by clas- 

 sing the genus Cottoniella as a representative of the two American 

 species, Cottoniella filamentosa and C. arcuata. 



In his above mentioned letter Dr. Howe suggested that the 

 two plants might perhaps be identical. However, according to the 

 description by Howe this does not seem to be the case, as several 

 differences are present. With reference to those we may first 

 point out that the monosiphonous filaments in my plant are ar- 

 ranged in zig-zag formation in two rows, as against one row in 

 Howe's. The upper ends of the branches in C. filamentosa do nob 

 seem to be archshaped like those in C. arcuata. And I have never 

 found in mine similar flattened parts of the filament, as shown 

 in fig. 2 or cross sections (3 or 4) in Howe's figures. Nor have 1 

 found such a well developed cortex as is shown in Howe's fig. 9, 

 whilst the oldest and thickest filaments in my plant looked like 

 my fig. 336 b. On the whole my plant seems to be a much more 

 dehcate plant than that of Howe. Therefore I think we have 

 to do with two different forms. 



When 1 described the plant 1 placed it, though with much 

 doubt, in the Fam. Rhodomelaceæ among "genera incertæ sedis", 



