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



This species resembles young conditions of U. zonata, and 

 even Hazen, on whose authority it is given, is in doubt if it 

 may not have to be included in the commoner species when bet- 

 ter known. The distinctions are in the darker color, thinner 

 cell wall and shorter cells, characters which are notoriously va- 

 riable in this genus. The only localities are near New York 

 city and in Alaska. Europe. 



5. U. OSCILLARINA Kutzing, 1845, p. 197; ? Wolle, 1887, p. 

 137, PI. CXVIII, figs. 34-36; Hazen, 1902, p. 150; P. B.-A., 

 No. 613. Forming soft mucilaginous masses; filaments about 

 ii /u. diam.; cells /^-/^ diam. long, rarely i diarn.; chromato- 

 phore a broad band. Mass. Europe. 



In quiet or slowly running water. The short cells and soft, 

 mucilaginous consistency are the chief distinguishing characters. 

 Wolle reports it from Wisconsin, but if his figure is drawn from 

 Wisconsin specimens, there might be some question as to the 

 identity of his plant with the present species. Hazen reports 

 the specimens in the Wolle herbarium not to be Ulothrix. 

 U. oscillarina appears to be a plant of summer rather than of 

 spring. 



6. U. MONILIFORMIS Kiitzing, 1849, p. 347 ; 1852, PI. 

 LXXXVIII, fig. 4; Hazen, 1902, p. 157; P. B.-A., No. 612. 

 Filaments 11-14 f- diam., more or less crisped, torulose, light 

 green, with thick walls ; cells about as long as broad. Europe. 



This may be the fruiting condition of some other species, but 

 it has not yet been identified with any, and it is quite distinct in 

 form from any of the species here recorded. It has only one 

 authentic locality with us, in Conn. 



7. U. AEQUALIS Kiitzing, 1845, p. 197 ; Wolle, 1887, p. 134, 

 PI. CXVIII, figs. 3-5 ; Hazen, 1902, p. 150 ; Phyk. Univ., 

 No. 577. Filaments 13-16 /Adiam., cylindrical, cells 1-2 diam. 

 long. Europe. 



A rather imperfectly known species, but considered quite dis- 

 tinct by Hazen. The only definite locality is near New York 

 City. 



8. U. ZONATA (Web. and Mohr) Kiitzing, i833a, p. 519; 

 Wolle, 1887, PL CXVII, figs. 1-19; Hazen, 1902, p. 147, PL 

 XX, figs. 1-4; P. B.-A., Nos. iga and 1023. Forming yellow- 

 ish green masses; filaments usually 30-40 \*. diam., sometimes 

 as low as 11 //. at the base of young filaments, rarely 45 /j. in old 



