i88 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



some undescribed species, it appears well to give the descrip- 

 tion here. 



H. SCALARIFORMIS G. S. West, 1905, p. 282, PI. CCCCL.XIV, 

 figs. 6 and 7. Cells narrowly oblong-ellipsoid, rather distant, 

 7-8.5 by about 2.5 /x, set transversely in the cylindrical, gelati- 

 nous filaments, 13-17 p- diam. Barbados. 



2. URONEMA L,agerheim, 1887, p. 517. 

 Filaments attached, simple, of a single series of cells, apical 



and basal cells attenuate ; chrornatophore a parietal disk, with 

 two pyrenoids, rarely only one pyrenoid ; asexual reproduction 

 by 4-ciliate zoospores produced singly, sometimes two, in any 

 cell of the filament, escaping by an opening, germinating at 

 once ; also by aplanospores, formed one in a cell. Only one 

 species. 



U. CONFERVICOLA Lagerheim, 1887, p. 518, PL XII, figs, 

 i-io; Wittr. and Nordst., Alg. Exsicc., No. 910. Filaments 

 up to i mm. long, solitary, cylindrical, apical cell acuminate, 

 basal cell attenuate, terminating in a callus; cells 4-6 p. diam., 

 2^-4 diam. long, basal and terminal cells considerably longer; 

 usualh^ attached to other algae. Fig. 66. W. I., Cal. Europe. 



Gaidukow, 1903, claims that under certain conditions a plant 

 that he designates as Ulothrix flaccida var. genuina Hansgirg, 

 developed filaments with pointed ends ; and that therefore Uro- 

 nema should be, at most, merely a subgenus of Ulothrix. There 

 might be some question as to what species Gaidukow had under 

 investigation ; Hansgirg gave a very broad extension to Ulo- 

 thrix flaccida, and his views on polymorphy of algae are well 

 known ; as here understood, Ulothrix flaccida Kiitz. belongs in 

 the genus Stichococcus, having only one pyrenoid to a cell, bicil- 

 iate asexual zoospores, and no differentiated basal cell. This 

 certainly does not agree with Uronema, and as U. confervicola has 

 been found in very distant stations, practically the same, it 

 seems best to retain it, pending further developments. 



3. RADIOFILUM Schtnidle, 1894, p. 47. 



Cells usually not as long as broad, subglobose, ellipsoid or 

 lenticular, with parietal chrornatophore and one pyrenoid, ar- 

 ranged in longitudinal series, in a wide, gelatinous, cylindrical 

 sheath. 



R. APICULATUM W. and G. S. West, 1895^ p. 52 ; Bohlin, 



