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MR. G. $. WEST ON SOME CRITICAL GREEN ALG, 
2XPLANATION OF THE PLATES. 
PLATE 20. 
Figs. 1-6. Polychetophora simplex, sp. п. х 400. 
Figs. 7-19. 
Figs. 20-30. 
Figs. 31-35. 
Figs. 40-43. 
1-5. Vegetative cells from the side showing the flexuose bristles and the single 
chloroplasts. 
6. Cell stained to show nucleus (п); the dark granules (s) are particles of 
starch. 
Brachiomonas submarina, Bohlin. x 1600. 
7-9. Three vegetative cells to show variability of external form. 
10, 11. Two individuals viewed from the anterior end to show the four lateral 
horns; 11 has three small pyrenoids (p', p^, and р”). 
12. Individual stained with gentian-violet to bring out the nucleus (4), and to 
show the extension of the cytoplasm to the extremities of the hollow horns. 
13. Individual after treatment with chlor-zinc-iodine : p, pyrenoid ; v, vacuole. 
14. 15. Anterior and side views of enlarged mother-cells containing four 
zoogonidia. These are disposed with their posterior horns directed towards 
a central point. 
16. Gamete. 
17. Zygospore. 
18. Distended individual only observed in cultures in Knop's solution after 
about three months. 
19. Monstrous specimen due to imperfect separation of two zoogonidia during 
their formation within the mother-cell. 
Kirchneriella subsolitaria, sp. n. x 1000. 
20-24. Solitary individuals; 20 is rather an unusual form. 
25. Solitary individual within a delicate membrane (probably the old wall of 
a mother-cell). 
26, 27. Colonies of two cells. 
28-30. Colonies of four cells; all enclosed in firm but delicate membranes, 
which are the old walls of the original mother-cells, but not gelatinized. 
PLATE 21. 
Phyllobiwum sphagnicola, sp. n. х 500. 
31. Edge of Sphagnum-leaf with nine resting-cells of the Alga attached to the 
ramifyiug vegetative threads: r.c., resting-cell; v.c., vegetative cell. 
32-35. hesting-cells attached to vegetative threads, isolated from the 
Sphaynum-leaves. 
Tetraédron platyisthmum, (Archer) nob. х 500. 
36. Cell showing chloroplast with one pyrenoid ( p). 
37. Empty cell in three positions. 
38. Empty cell. 
39. Empty cell with longitudinal slit (4), possibly formed for the escape of 
autospores. 
Chodatella quadriseta, Lemm. X 1000. 
In 41 and 42 the chloroplast has become separated into two parts. 
LINN. JOURN.—BOTANY, VOL. XXXVIII Y 
