FRESHWATER ALG^E 271 



SYSTEMATIC ACCOUNT OF SPECIES OBSERVED 

 CHLOROPHYCE^E 



ULOTRICHACE.P 



Genus ULOTHRIX Kiitz. 



1 Ulothrix subtilis Kiitz. 



Phyc. Germ. 1845, p. 197 ; Tab. Phycol. II, 1852, t. 85, f. 1 ; Rabenh. Flor. Europ. 

 Alg. III., 1868, p. 365. 



Var. variabilis (Kiitz.) Kirchner, Alg. Schles. 1878, p. 77. U. variabilis Kiitz. 

 Spec. Alg. 1849, p. 346 



Crass, fil. 6-7 M ; cellulis diametro lj- 2-plo longioribus. 



Hob. In pond, Cape Royds. 



The specimens were a trifle thicker than the average for this plant, but they are 

 referable to no other species of the genus. Some of the more elongated cells had 

 formed " thin- walled aplanospores," which were germinating while still within the 

 original mother- cell. It is possible that this may have been the germination of 

 incompletely formed zoogonidia, a phenomenon which occurs not infrequently in 

 U. zonata, but the material did not admit of a determination of this point. 



2 Ulothrix tenerrima Kiitz. 



Phyc. gen. 1843, p. 253, t. 9, f. 1 ; Phyc. Germ. 1845, p. 197 ; Spec. Alg. 1849, 

 p. 346 ; Rabenh. Flor. Europ. Alg. Ill, 1868, p. 366. U. tennis Kiitz. Spec. Alg. 

 1849, p. 346. 



Forma antarctica. (PI. XXIV, Figs. 5-7) 



Forma filis brevissimis, flexuosis vel subcontortis, libere natantibus inter algas 

 varias Myxophycearum ; cellulis plerumque brevibus, diametro J-l-plo longioribus. 



Crass, fil. 7-8 M . 



Hob. Green Lake. 



The extreme shortness of the filaments and their bent character are the distin- 

 guishing features of this form. It should be emphasised that this form was growing 

 in very saline water, with a much greater concentration of salts than in sea- water. 



3 Ulothrix implexa Kiitz. 



Spec. Alg. 1849, p. 349 ; Tab. Phycol. II, 1852, t. 94, f. 2 ; Hazen in Mem. Torr. 

 Bot. Club, xi, No. 2, 1902, p. 153, t. 21, f. 1, 2. 



Crass, fil. 11.5-12.5 p.; cellulis plerumque paullo inflatis, diametro f-l-plo 

 longioribus. 



Hab. High moraines, Mt. Erebus. 



BRIT. ANTARCT. EXPED. 1907-9. VOL. I. K 



