266 W. AND G. S. WEST 



(a) December 1908. Great quantity of Nostoc antarctica with many diatoms. 



(b) December 1908. Large quantity of Nostoc antarctica with several Green 

 Algse. 



(c) January 26, 1909. Half a mile from camp. Mostly Ulothrix subtilis var. 

 mriabilis, with several blue- green filamentous forms, including Oscillatoria terebri- 

 f or mis forma tennis, and 0. amphibia var. robusta. 



3 Green Lake, Cape Royds 



Half a mile from camp. Coll. J. Murray. Three collections were made: 



(a) November 29, 1908. Some open water on the lake. 



(b) January 3, 1909. Temperature of open water 36 F. 



(c) February 2, 1909. Temperature of open water 35 F. On this day the lake 

 became frozen over again. 



The water of this lake is very saline, and there is always a little water under the 

 ice. Owing to its remarkable salinity, the fluid obtained from under the ice at the 

 time when it was thickest did not freeze until the temperature was reduced to 7 F. 

 On June 26 the temperature under the ice was 21 F., and on August 6, 1908, it was 

 8 F. 



The lake contained twenty-six species of Algse, among which the Myxophyceae 

 predominated. These Blue- green Algae were free-floating in the briny liquid, no 

 extensive sheets being developed. The Green Algse occurred mostly in February. 

 Eleven species of diatoms were observed, almost all of which were marine forms. 

 Two of them, however, Navicula muticopsis and N. (Pinnularia) globiceps, occurred 

 plentifully in other situations which were not so saline in character. 



We append a complete list of the species of Algse which lived in association under 

 the conditions of great salinity prevailing in this lake : 



Ulothrix tenerrima Kiitz. forma antarctica. 

 U. cequalis Kiitz. forma. 

 Pleurococcus angulosus Lagerh. forma. 

 PI. antarcticus sp. n. 

 PL dissectus (Kiitz.) Nag. 

 Trochiscia aspera (Reinsch) Hansg. 

 Coscinodiscus lentiginosus Jan. 

 Hemiaulus ambiguus Jan. var. 

 Triceratium arcticum Btw. 

 Fragilaria obliquecpstata V. Heurck. 



forma maxima V. Heurck. 



Navicula muticopsis V. Heurck. 

 2V. (Pinnularia) globiceps Greg. 

 Trachyneis aspera (Ehrenb.) Cleve. 

 Tropidoneis Iwvissima sp. n. 



