406 Notes on the Blue-green Alge, etc. 
65. Trichomes not capitate, transverse walls not granular os OO 
65. Trichomes especially capitate, transverse walls with 
well-marked granules. (See No. 60.) .. P. favosum 
66. Stratum thick, compact mass, or tufted, bright 
blue-green, sometimes lead coloured .. P. retzii 
Filaments straight, fragile, sometimes 
moniliform,* usually not; trichomes 4:5- 
I2 mic. in diameter, cells 4-9 mic. long ; 
cell contents granular (metachromatin 
granules), transverse walls not granulated ; 
central body (nucleus) clearly visible 
especially when stained; apex straight, 
not capitate, apical cell truncate, with 
scarcely thickened membrane. The plant 
is of frequent occurrence in still and 
running water in limestone districts, and 
is an excellent type for cytological study. 
(Ge 175;1'5; 0-9 5 02; 5, 21-48) 
Var. fasciculata. Tufted, floating, in 
rapidly running water; not moniliform. 
Var. rupestris. In still water; monili- 
form, especially near the apex. 
66. Stratum thin, dark blue-green é O. minnesotensis 
Trichomes much constricted at joints, 
not tapering, not capitate; cells 2-5 mic. 
in diameter, 2-4 mic. long; apical cell 
rounded, no calyptra. On sides of a 
quarry under dripping water. (T., 75, 
4, 21.) 
66. Stratum amorphous, gelatinous, fibrous, in 
the meshes of a sponge; salt water .. P. spongeliz 
Trichomes brownish-red, much _ con- 
stricted at joints; hormogones frequently 
attenuate at each end; cells 7:5-8-5 mic. 
in diameter, 2:7-7:3mic. long; apex 
rounded, no calyptra. (G., 161, 4, 8-10.) 
67. Cells shorter than the diameter .. a .. 0. cruenta 
Stratum dark purple; cells 4-7 mic. in 
diameter, 2-4 mic. long; transverse walls 
granular; apex obtuse, straight or 
slightly curved. (T., page 8o.) 
67. Cells equal in length to or longer than the diameter es <toghOS 
68. Stratum thin, beautiful blue-green; cell con- 
tents pale blue-green a . O. amphibia 
Trichomes 2-3 mic. in diameter, straight 
or curved, fragile, not constricted at 
joints ; cells 4-8°5 mic. long, transverse 
walls with two granules; apex not 
tapering, not capitate, no calyptra. In 
fresh water, cold or warm, on rocks, damp 
soil, in effluent from filter beds, etc. (G., 
221, 7,045 pal eats 0k Og 2) 
(To be continued). 
7-O:; 
The Museums Journal for October contains a paper on ‘ Methods of 
Collecting,’ by Mr. Sheppard, which makes one wonder whether curators 
possess consciences. 
Naturalist, 
