520 PLANKTON OF THE SYDNEY WATER-SUPPLY, 



Genus Dactylococcopsis Hansgirg. 



D. MONTANA W. & G. S. West. 

 Long. cell. 8-15; lat. 2-3 /x. 



D. RAPHiDloiDKS Hansg. 



Ccen. long. 55-77; lat. 7-11 /x. 



Cell. long. 14-32; lat. 2^-3 /x. 



I am decidedly of opinion that this is a degenerate fox'm of 

 Spirotceina acuta Hilse, which I have found at Fairfield in a 

 pool, into which a scour from the Water-Supply drains. Coen. 

 77x22, cells 40x10, bright green chloroplasts with a single 

 pyrenoid. It is no objection that the endoplasm is homogeneous 

 in D. raphidioides, as this is the case in most young and degen- 

 erate forms of unicellular algse. Spiro. tenerrima Arch., is pro- 

 bably an intermediate form, vide VV. it G. S. West, Monog. Br. 

 Desm., PL iii., f. 16-1 7. 



Genus CHiEXOSPHiERiDiUM Klebahn. 



Oh. GLOBosuM(Nord.) Klebahn. 

 Cell. diam. 12, probos. long. 8 }i. On Spirogyra filaments. 



Var. MiciioscopicuM, u.var. (Plate Ivi., fig. 12). 

 Forma minulissima, cellulis sphaericis setis singulis longis- 

 simis instructis, endochroma homogenea. 



Cell. diam. circ. 1 /x. On Oedoyoiiiuni and Melosira. 

 This is probably the very smallest size of Ch. globosum, the 

 outgrowth of a micro-zoospore. 



Subfamily P H y t H E l i E ^. 



Forms of Layerkeirnia and Chodatella were present in 

 almost all the samples from the filter-screens, being most 

 abundant in J vine (winter). At first, an attempt was made 

 to distinguish between the two genera (in spite of the fact 

 that in no single instance were there any basal tubercles to 

 the setas) under the impression that the setae in Chodalella 

 were, at least, less robust than those of Lar/erheiniia. This 

 theory, however, proved untenable, it being found that the 



