286 University of California Publications in Botany [Vol. 8 



4. Ulothrix laetevirens (Kuetz.) Collins 



Filaments 10-25/x diam., two or three often firmly grown together 

 laterally, more or less entangled and creeping ; with not infrequent 

 branches, issuing at a wide angle, and usually much more slender than 

 the main filament, of many cells, which are generally 1-3 diam. long ; 

 filaments tapering towards the base, the lower cells of the densely 

 packed filaments often subparenchymatously united ; cells 0.25-0.75 

 diam. long, rarely more ; chromatophore covering nearly or quite 

 all of the cell wall, but thicker at one side, where the pyrenoid is 

 situated; zoospores usually 8 in a cell; akinetes formed singly from 

 the cells. 



On woodwork between tides. Alaska (Unalaska and Sitka) to 

 California (fide Collins). 



Collins, Green Alg. N. A., 1909, p. 186. Schizogonium laetevirens 

 Kuetzing, Phyc. Germ., 1845, p. 194. Ulothrix consociata Wille, Stud, 

 ueb. Chloroph., I-VII, 1901, p. 25, pi. 2, f. 82-89, Algol. Unters., 

 I-VII, 1906, p. 12, pi. 1, f. 30, 31 (fide Collins). 



Collins (1909, p. 186) considers that Schizogonium laetevirens 

 Kuetz. and Ulothrix consociata Wille are identical. He formed his 

 opinion after examining a topotype of Kuetzing's species. We have 

 adopted this opinion, but have formed our idea of the species upon 

 the description and figures of Wille. Our specimens show fairly fre- 

 quent branches and filaments laterally coalescent. In dimensions, 

 both of vegetative and fertile segments and cells, our specimens agree 

 closely with the plant described and figures by Wille. The plant has 

 a considerable likeness to U. pseudoflacca Wille, but it is to be dis- 

 tinguished by its tendency to branch and to have coalescent filaments. 



FAMILY 12. CHAETOPHO'RACEAE de-toni and levi 



Frond of more or less branched filaments, erect or prostrate, at 

 times enclosed in a more or less gelatinous envelope ; cells uninucleate, 

 green, without haematochrome, the terminal often acvite or forming 

 a colorless hair; chromatophore parietal, band-shaped, at times an- 

 nular, containing one or more pyrenoids ; propagation vegetative, by 

 akinetes or by^ aplanospores ; zoospores of two sorts, macrozoospores 

 and microzoospores, 2- 4-ciliated, usually produced from modified 

 cells; 2-ciliated isogametes and heterogametes known in some genera; 

 setae of various kinds present in some genera. 



