Fig. 18. Pediastrum simplex. — Fig. 19. Pediastrum elegans.
P L A T F L X X X V I I .
Fig. 1. Closterium Ehrenhergii. — Fig. 2. Closterium monili-
ferum. — Fig. 3. Closterium turgidum. — Fig. 4. Closterium
striolatum. — Fig. 5. Closterium acerosum. — Fig. 6. Closterium
rostratum. — Fig. 7. Closterium setaceurn.
P L A T F L X X X V I I I .
Fig. 1. Closterium lineatum. — Fig. 2. Closterium Cornu.
— Fig. 3. Closterium Trabecula. — Fig. 4. Closterium Digitus.
— Fig. 5. Closterium margaritaceum.
P L A T E L X X X IX .
Fig. 1. Xantliidium furcatum. — Yig. 2. Xanthidium fascicu-
latum ? — F ig. 3. Xanthidiurn aculeatum ; a, front view; b,
end view; c, side view; d, new segment. — Fig. 4. X a n -
thidium polygonum. — Fig. 6. Tetmemorus granulatus: a,
front view ; b, side view ; c, empty fro n d ; d, fronds conjugated,
sliow’ing mode of formation of the sporangium; e,
sporangium perfectly formed. —■ F ig. 5. Tetmemorus Bre-
bissoni; a, front view; b, side view; c, empty fro n d ; d,
segment of frond.
P L A T E XC.
Fig. 1. Micrasterias rotata: a, adult frond ; b, c, young fronds
of same ; d, showing the mode of formation of the new
segment.—^ Fig. 2. Micrasterias radiata. — F ig. 3. Holo-
cystis oscitans? {Euastrum crux melitensis, young, E hr.) —
Fig. 4. Holocystis oscitans. — Fig. 5. Euastrum circulare,
— F ig. 6. Euastrum. — Fig. 7. Micrasterias crux melitensis
(^Euastrum crux melitensis Ehr.). — Fig. 8. Euastrum D idelta
: a, front ; b, side view. — F ig. 9. Euastrum affine: a,
front ; b, side view. — Fig. 10. Euastrum.
P L A T E X C L
Fig. 1. Euastrum oblongum : a, front ; b, side views ; c, empty
frond. — Fig. 2. Euastrum insigne. — Fig. 3. Euastrum
Pelta : a, front ; h, side view ; c, empty frond. — Fig. 4.
Euastrum binale. — Fig. 5. Variety of same. — Fig. 6.
Euastrum gemmatum : a, front view ; b, side ditto ; c, d,
end view ; e, variety. — Fig. 7. Euastrum verrucosum : a,
front view of young frond ; b, ditto of adult frond ; c, side
view; d, end view. — Fig. 8. Euastrum rostratum.— Fig. 9.
Euastrum spinosum : a, b, d, e, f , front view, and showing
the mode of formation of new fronds ; c, end view. —
Fig. 10. Euastrum. — Fig. 11. Euastrum Didelta: a, front
view ; b, transverse ; c, d, end views.
P L A T E X C II.
Fig. 1. Pediastrum tricyclium.—Fig. 2. Pediastrum ellipticum.
— Fig. 3. Pediastrum lunare. ■— Fig. 4. Pediastrum cribri-
forme.— Fig. 5. Pediastrum hexactis.— Fig. 6. Pediastrum
excavatum. —Fig. 7. Pediastrum Botula. — Fig. 8. Pedias-
trumincisum.— Fig. 9. Pediastrum beptactis.— Fig. 10. Pediastrum
Napoleonis.— Fig. 11. Pediastrum Napoleonis var.
— Fig. 12. Scenedesmus quadricaudatus : a, frond in its ordinary
state ; b, var. with three spines ; c, var. destitute of
spines. — Fig. 13. Scenedesmus dimorplius.—Fig. 14. Scenedesmus
acutus.—-Fig. 15. Scenedesmus triseriatus. — Fig.
16. Scenedesmusobtusus.—Fig. 17. Cylindrocystis Brebissoni.
P L A T E X C I I I .
Fig. 1. Sphærophora globulifera. — Fig. 2. A portion of a
filament of Meloseira arenosa. Fig. 3. End view of a
frustule of the same. — Figs. 4 and 5. Meloseira varians.
— Figs. 6 and 7. Meloseira oriclialcea. — Figs. 8 and 9.
Tetracyclus lacustris. — Fig. 10. Bacillaria paradoxa.
P L A T E X C IV .
Fig. 1. Diatoma vulgare. Fig. 2. The same as in a more
advanced stage of its developement. — Fig. 3. Diatoma