COSMOCLADIUM. 201 



tical. Chloroplasts axile, with a pyrenoid in the centre 

 of each semicell. Cells united into colonies by means 

 of gelatinous threads, sometimes with a tree-like habit 

 and attached to other larger filamentous algae (according 

 to de Brebisson). 



Zygospore unknown. 



Length of cells 12-24^ ; breadth 11-16^ ; thickness 

 6-7 u ; breadth of isthmus 4-4'5 a. 



SCOTLAND. Aboyne, Aberdeen ; Bogandreep in Glen 

 Dye, Kincardine; Clova Tableland, Forfar (Roy & Biss.). 

 Rhiconich, Sutherland ! Near Tarbert, Harris, Outer 

 Hebrides ! 



Geogr. Distribution- -France. Germany. United 

 States. 



4. Cosmocladium pusillum Hilse. 

 (PI. CLYIIL figs. 8-10.) 



Cosmocladium pusillum Hilse in Bericht. d. Schles. Ges. 18(55. p. 117; in 

 Rabenh. Alg. Eur. 1867, no. 1963; Rabenh. Flor. Europ. Alg. 1868, 

 p. 54 : Kirchn. Alg. Schles. 1878. p. 105 ; De Toni, Syll. Alg. 1889, p. 805. 



Cosmocladium subramosum Schmidle, Chlorophy.-H. Torfstiohe Virnheim, 

 1894. p. 49, t. 7, f. 8 ; West & G. S. West, All'. X. Ireland, 1902, p. 42, 

 t. 2, f. 13, 14. 



Cells small, up to 1^ times longer than broad, deeply 

 constricted, sinus linear for most of its length, then 



o 



opening more widely ; semicells oblong-elliptic, apex 

 somewhat flattened, sides broadly rounded ; in end-view 

 elliptical ; chloroplasts axile, with a pyrenoid in the 

 centre of each semicell. Colonies usually small, rarely 

 consisting of more than 8 cells, only very slightly or 

 not at all branched, free-floating ; cells mostly with 

 their broad surface perpendicular to the direction of the 

 connecting gelatinous threads ; colonies sometimes en- 

 veloped in a very thin, scarcely- visible mucus. 



Zygospore unknown. 



Length of cell ll-12[j. ; breadth 11 -12u ; thickness 

 5-6 [JL ; breadth of isthmus 2-3 pt. 



IRELAND.- -Lough Anna, Donegal ! Rare in the plank- 

 ton of Gal way. 



Geogr. Distribution. Germany. Finland. 



