BY G. I PLAYFAIR. 841 



Coenob. diam. 96-112; cell. long. 20-27, lat. 4-8/x. 



Botany. 



The coenobium consists of a mucous sphere, as in Sphfcrocystis 

 or Gl(jeocyi<tis, with lunate cells, generally in groups of 4, which 

 appear to be either joined loosely by the extremities, or radiate 

 from a common centre. 



Genus Tetrallantos Telling. 

 Tetrallantos Lagerheimii Telling. (PI. Iviii., f.9, 10). 

 Ccenob. (4 cell.) long. 38-40, lat. 20-24; (8 cell.) 54 x 20; cell, 

 long. 12-16, alt. 6-12, crass. 3-6/x. 



Botany (37, 152); Botanic Gardens (125); Lismore (258, 260). 

 Cf. Einar Teiling, Schwedische Planktonalgen, ii., Tetrallantos, 

 eine neue Gattung der Protococcoideen, p.63, f. 1-7, 1916. 



Genus Tetraedron Kiitz. 

 Tetraedron minimum (A.Br.) Hansg. (PI. Iviii., f.ll). 



Cell. long. = lat. = Q-^fx. 



Parramatta Park (136); Guildford (88); Lismore (260, 276). 



PoJyedrium minhnum A. Braun, Alg. unicell., p. 94, footnote;- 

 G. S. West, Brit. Frw. Alg., p.231, fig. 101a. The type has 

 rather acute, radiating angles, and emarginate sides, alternate 

 sides more deeply emarginate ("lateribus alternis projundius 

 emarginatis" — A. Braun, I.e.) than the others. There are several 

 well-marked forms of the species. 



Var. australe, n.var. (PI. Iviii., f. 12, 13). 



Cellulte lateribus alteris planis levissime convexis, alteris 

 altissime emarginatis. 



Cell. diam. 5-8/x. Botany (95); Lismore (180, 276). 



Cell. diam. 10-12/x. Botanic Gardens (3); Casino (189). 



The most common form of the species here. The ends are flat 

 or nearly so, slightly turned down at the angles, while the sides 

 are very deeply emarginate and arched. In shape, it resembles 

 Tpfr. platyisthmium (Arch.) G. 8. West, "Some ci'itical green 

 Algte," p.286, P1.21, f.36-39, but is very much smaller, and cei-- 



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