Notes on the Blue-green Algae, etc. 335 
1 eats of the cells constricted de Ee bie tee 
13. Joints of the cells not at all constricted . its fig eee 2. 
14. Torulose or moniliform .. ate ee eT Imes 
14. Not torulose or, in specimens, slightly s so x st Say 2 
15. Torulose. ne Pr Ee He ai oye srs 
15. Not torulose Se 3: a se Ee cee xe, eReaE 
16. Thermal .. 2s Be ine .. O. geminata 
Stratum dull yellowish-green ; __ tri- 
chomes 2-3-4 mic. in diameter, curved or 
rolled, much constricted; apex straight 
or curved, not tapering, not capitate ; 
apical cell rounded, no calyptra; cells 
2°3-16 mic. long, with large Bre 
granules in the cytoplasm. (G., 222, 7, 6; 
T., 74-) 
16. Fresh water or terrestrial be Bt <3 ne Bolts 
17. Thermal, trichomes -6--8 in diameter os ..  P. treleasei 
Stratum of many papery layers; tri- 
chomes 6-8 mic. in diameter, not con- 
stricted at joints; apex straight, rigid, 
not tapering, obtuse, no calyptra; cells 
up to 8-8mic. long. (T., 96.) 
17. Sheath visible .. ote or ae oe (20; 
17. Sheath not present, not visible ee Si = < 3 oe ey 
18. Plants found in salt waters... -- ©. bonnemaisonii 
Trichomes 18-36 mic. in diameter, form- 
ing loose and regular spirals, somewhat 
constricted at joints; apex not tapering, 
not capitate, no calyptra; cells 3-6 mic. 
long, transverse walls not granulated. On 
wet soil, salt marshes, marine alge, etc. 
(G.,.215, 6, 17-18; Tie 68, 4, 10, 
18, Plants in fresh water .. at Ae Lea] O 
1g. Cells nearly as long as broad or longer if. th ex sone OF 
1g. Cells half as long as broad or shorter de ag g. er As: 
20. Calyptra absent .. re ze .. 0. princeps 
Stratum dark green ; trichomes 16-60 
mic. in diameter, commonly 25-50 mic., 
straight, rigid; apex sub-capitate, 
slightly tapering, more or less uncinate ; 
cells 3-5-7 mic. long, transverse walls not 
granulated. Of frequent occurrence in 
ponds and quiet waters on the mud, then 
floating? (Gi 206; 6.1.01, T., 62547 37) 
20. Calyptra present, or apical membrane thickened a ory 2 
21. Cells equal in length to the diameter or longer 
P. submembranaceum 
Stratum leathery, dark green, sheaths 
absent; trichomes 5 mic. in diameter, 
constricted at joints, tangled, agglutinated; 
apex straight, tapering, capitate, calyptra 
conical; cells 4-10 aa long. (G., 180, 
5, 13; ae 104, 5, 6.) 
. Cells shorter in length than their diameter ..  P. lucidum 
Stratum black green, underneath layers 
more or less decoloured ; trichomes 7-8 
mic. in diameter, slightly flexuous, 
slightly constricted at joints; cells 2-2°5 
long, transverse walls eranular ; apex 
straight, more or less tapering, capitate ; 
I913 Sept. 1. 
