FRESHWATER ALGM 279 



Genus HEMIATJLUS Ehrenb. 



20 Hemiaulus ambiguus Janisch 



Var. V. Heurck, Diatomees, Result. Voyage du s.y. "Belgica," Anvers, 1909, t. 8, 

 f. 110. 



Diam. valv. 60 /u. 



Hob. Green Lake. 



Dr. Van Heurck was apparently somewhat doubtful concerning the exact 

 determination of his specimen (I.e. p. 36). Those observed from the above locality 

 were in exact agreement with his figure. 



TABELLARIACE.E 



Genus TABELLARIA Ehrenb. 



21 Tabellaria flocculosa (Roth.) Kiitz. 



W. Sm. Brit. Dial. II, p. 45, t. 43, f. 316. V. Heurck, Synops. Dial. Belg. t. 52, 

 f. 10-12. 



Long. valv. 26-27 n ; lat. max. ad med. 9.5-10 fj. 



Hob. Ponds on slopes of Mt. Erebus. 



In his Synopsis of Naviculoid Diatoms, Part I., 1894, p. 12, Cleve states that " of 

 Tabellaria flocculosa, one of the most frequent diatoms of Europe, not a trace has 

 been found either in S. America from Ecuador to Argentina, or in Australia or New 

 Zealand." Recently, however (G, S. West, " Alg. Yan Yean Reservoir," Journ. Linn. 

 Soc. bot. xxxix, 1909, p. 30), this cosmopolitan species has been shown to be abundant 

 in at least one district of Victoria, and the examples from Mt. Erebus were in every 

 way typical. Moreover, the specimens were in no way fragmentary, but had been 

 fixed in the living state, although the colonies were not observed to consist of more 

 than two cells, possibly owing to the rigorous conditions of existence. 



FRAGILARIACE^ 



Genus FRAGILAEIA Lyngb. 



22 Fragilaria tenuicollis Heib. var. antarctica var. n. (PI. XXVI, Fig. 128) 



Var. polis valvso valde productis et leviter subcapitatis ; striis non radiatis, 16 in 

 10 ft. 



Long. valv. 37 M; lat. 3 /u. 



Hob. Clear Lake. 



In outward form the valves were very similar to F. tenuicollis var intermedia 

 (Grun.) V. Heurck [ = F. intermedia Grun. ; V. Heurck, Synops. Diat. Belg. t. 45, f. 9"!, 

 but they did not possess the median unilateral central area which is characteristic of 

 that variety. 



BRIT. ANTAKCT. EXVED. 1907-9. VOL. I. L 



