loo felOLOGY OF THE RlCfiMONt) RIVER, 



tions. I have ventured, however, to move it to the genus Penium^ 

 as the arrangement of the chloroplasts is not at all that of Cos- 

 marium {seiisu stricto). 



Genus Closterium Nitzsch. 

 Four forms of Closterium rather common in the river at I>.is- 

 more are CI. Ehrenhergi% CI. Leibleinii, CI. tnoniliferuin and CI 

 incurvum. I consider these are forms of the same species, the 

 difference being a mere matter of development. The zygospores 

 also of 67. Ehreubergii and CI. moniliferuin are identical, Monog., 

 i., pp.143, 144, PL 17, f.4. The last three were found together at 

 Kyogle also. 



Closterium acerosum (Schrank) Ehr. 

 Long. 460-655, lat. 42-50, ap. 6 ju. 

 Lismore(3, 16, 19), Casino (14). 



Fairly plentiful: the membrane pale pink, smooth or very finely 

 and faintly striate, 10-12 ridged chloroplasts, 11-20 pyrenoids in 

 semicell. The edges of the chloroplasts are sometimes scalloped 

 towards the apices of the cell. 



Var. lanceolatum (Kiitz.) mihi. (67. lanceolatum). 

 Long. 300-310, lat. 48, ap. 6 /x. 

 Lismore(22). 

 CI. lanceolatum is only a short form of 67. acerosiim. 



Var. Angolense W. t G. H. West, f. (PI iii., f.4). 

 Forma semicellulis infra apices ut in 67. turgido incrassatis; 

 polls levissime recurvatis: apicibus extremis ut in CI. nceroso 

 truncatis. Membrana hyalina (apicibus extremis exceptis) vel 

 dilute rufescente. Interdum ad suturam zona intercalata (lat. 

 6/x). 



Long. 840, lat. 40. ap. 6//. 

 Casino (14). Cum priori et sequenti. 



Cf. W. & G. S. West., Monog., i., p.l49, P1.18, f.6. Thisform 

 combines in itself the characteristics of four " species."' It has 

 the extreme tip of CI. acerosum, the size and shape of CI. acero- 

 sum var. Angolense, the recurved ends and slight curvature of 

 CI. Pritchardianum, and the subapical incrassate zone of 67. 

 turgidum. 



