FRESHWATER ALG^E. 55 



PLATE I. 



FIGS. 1-5. Chlamydomonas *itlii-iiinl/it//. Wille, ordinary individuals, cf. description, pp. 7, 8 ; ^, pyrenoid ; 



// = nucleus, (x 700.) 

 FIGS. Q-lO.ChleanydemoiUU xulirtni'/nta Willc, encysted individuals. In tigs. and 7 the original shape 



of the mother-cell membrane is easily recognised ; in figs. 8-10 the cysts show the 



processes described on p. 8 ; /; = pyrenoid ; n = nucleus. ( x 700.) 

 Fids. 11-14. Chlamydomonas eubeaudata Wille, free cysts; in fig. 14 the cyst contains two pyrenoids. 



(X 700.) 

 Fids. 15-18. Chlamydomoncu intermedia Chod., ordinary individuals ; p = pyreuoid ; n = nucleus ; c = 



contractile vaeuolc ; x = stigma. ( X 1350.) 

 FIG. 19. L'l/lamydommias ehrenbcrgi Gorosch., ordinary individual ; p = pyrenoid ; n = nucleus. 



(X 700.) 



FIG. 20. CMamydomonas subraudata Wille, cyst showing division of contents into four parts, (x 700). 

 Fics. 21-25. Ghloromonais nlpina Wille ; n = nucleus ; s = eye-spot. In most of the individuals the 



cilia could not be traced to their full length, (x 1350.) 



Fie;. 2(i. Pleurococcus anlarctir-us W. and 0. S. West, f. typim ; o = oil-globules, (x 550.) 

 Kid. 27. f.minor. (X 550.) 



FIG. 28. f . fila menlosa. (x 550.) 



FIG. 29. ., LsMlata. (x 800.) 



FIGS. 30, 31, 33. ., f. simplex; o = oil-globules, (x 550.) 



FIG. 32. ., ., f. tt/pica, a group of appreciably larger cells than 



those in Fig. 20. One of these cells has two pyrenoids. ( X 400.) 

 FIGS. 34-35. Pleurococcus antardicus W. and G. 8. West, f. robusta, elliptical cells, (x 500.) These 



are relatively small cells of this form. 



FIG. 36. Pleurococcus koettlitzi sp. n., group of cells seen at a low magnification, (x 220.) 

 FIGS. 37-42. Pleurococcus koettlitzi sp. n. ; 37, 39, 41, ordinary tetrads ; 38, small part of group shown 



in fig. 36 ; 40, development of daughter-cells within mother-cell ; 42, development of 



daughter-cells within mother-cell, some of the cells of the tetrad are abortive. 



(39, 40 X 500 ; other figures X 400.) 



FIGS. 43, 44. Pleurococcus friyidus W. and G. 8. West, (x 400.) 

 FIGS. 45, Q.Penium sp., cf. pp. 20, 21. ( x 500.) 

 FIGS. 47, 48. Eucapsis minuta sp. n. 47, Surface view of &n older colony to show grouping of cells 



( x 1800) ; 48, Diagram of eight cells of colony to show the cubical arrangement 



(magnified about 4000 times). 



FIGS. 49-51. Merismopedia tenuissima Lemm. ; 49, young colony ; 50, 51, older colonies. (X 1400.) 

 FIG. 52. Phormidium frigidum sp. n. (x 1800.) 



FIGS. 53, 54. Phormidium autumnale (Ag.) Gom., apices of two filaments. ( X 700.) 

 Fids. 55-59. O-willatoria Itoettlitzi sp. n. ; 55, 57, 58 are typical trichomes. (X 700.) 

 FIGS. 60-04. Oscillatoria simplicissima Gom., var. antarctica var. n. ; 62, f. acuminata; 61, f. spiralis ; 



64, trichome overgrown by filaments of Phormidium anijustissimum. (X 550.) 

 FIG. bb.0scilla!oriaproducta W. and G. S. West. (X 800.) 

 FIG. 66. subproboscidea W. and G. S. West, (x 800.) 



FIGS. 67-70. Microcyslis parasitica Kiitz. (x 700.) 

 FIGS. ll-TS.Phormidiwn antarcticum W. and G. S. West, forma. (71, 72, x 850 ; 73, X 1800.) 



