NOTES ON THE BLUE-GREEN ALG&, 
WITH A KEY TO THE SPECIES OF OSCILLA- 
TORIA AND PHORMIDIUM. 
HAROLD WAGER, F.R.S. 
(Continued from page 406). 
68. Stratum thin, cob-webby, yellowish green ; cell 
contents orange or yellowish green 
Trichomes 3°5-4 mic.’ in diameter, 
straight or curved, fragile, not constricted 
at joints; cells 3-7-8 mic. long, transverse 
walls not granular ; apex not tapering, no 
calyptra. In stagnant water; on de- 
caying vegetable matter in water. (G., 
223; T., 75, 4, 22.) 
69. Trichomes -6 mic. in diameter; cell contents light 
blue-green .. O. 
Stratum expanded, blue- green; tri- 
chomes not constricted at joints, flexuous, 
entangled ; cells -:9-1-:2 mic. long, trans- 
verse walls not distinct; apex not taper- 
ing, not capitate. In ponds. (T., 76.) 
69. Trichomes I-1-5 mic. in diameter; cell contents 
vellowish green aie. oO. 
Trichomes solitary or scattered, rarely 
in a yellowish-green mass, straight or 
circinate ; cell walls inconspicuous. (L2 
74- 
JO. Sheath visible 
Stratum thin, dull ¢ green to olive e brown : 
filaments 15-18 mic. in diameter ; sheaths 
wide, firm, colourless ; trichomes fre- 
quently interrupted; cells two or three 
times shorter than the diameter, indis- 
tinct. In pools; on marshy grounds, 
etc, 7 (la;/ 1620 4h 970%) 
70. Sheath not visible 
71. Trichomes straight 
Stratum dark blue-green; tiichomes 
straight, not constricted at joints, trans- 
verse walls frequently granular; cells 
I1-20 mic. in diameter (commonly 13-16 
mic.), 2-5 mic. long; apex straight, not 
at all or scarcely tapering for a short dis- 
tance, not capitate; apical cell convex, 
with ‘slightly thickened walls. In quiet 
or gently-moving water. (G., 210, 6, 13; 
A 65, 4, 6.) 
71. Apex of trichome uncinate or lax spiral .. 
1913 Dec. r. 
Stratum light or dark blue-green; tri- 
chomes straight below, not constricted at 
joints; cells 10-17 mic, in diameter, 2-5 
mic. long, transverse walls sometimes 
granular; apex not or scarcely tapering, 
not capitate ; apical cell convex, sometimes 
slightly thickened. In quiet or gently- 
O. chlorina 
angustissima 
subtilissima 
P.naveanum 
O. Jimosa 
O. curviceps 
3 
