139 
ple, long, olivaceous, brownish-yellow, or dull aeruginous. Mature 
plant not articulate, or very indistinctly so, except the rather 
long, thin, colorless ends, in which the divisions are two to 
four times as long as wide. Filament linear, granular. Sheath 
rarely seen. Heterocysts spherical, rather smaller than the adjoining 
cells. Plants vary greatly in length, from 10 to 100 and more diam- 
eters. The young plants are distinctly articulate, usually one large 
cell next the heterocysts ; other divisions about as long as wide; 
filaments at first in a horizontal position, one on the other ; as they 
mature they become erect and tortuous, caespitosely attached.  Fil- 
aments .0003” to .o004” in diameter. 
M. lutea,n:sp. Strata thin ochreous, filament aggregated, suberect 
or flexuonsly curved, simple. Trichoma bright brownish-orange, dis- 
tinctly articulate, articles half as long as wide, and usually separated 
by a distinct space. Sheath ample, often twice as wide as the trich- 
oma, and tinged with the same color, or colorless, firm, slightly 
attenuated, generally open at the apex, and extending beyond the 
trichoma. Heterocysts oblong-globular. Sheath .00084” below, 
tapering to .0005”. Partly exposed stones in spring water. 
16. Diplocolon.—D. Heppii, Naeg., Niagara. 
17. Scytonema, Ag.—Sc. tolypotrichoides, Ktz. In gelatinous 
masses on dripping rocks.—Sc. Hegetschweileri, Itz. Forms a dark 
brown coating on wet rocks, Niagara; differs very slightly from the 
European form. Probably the same plant Dr. Wood described un- 
der the name, Sc. cataracta. See Rabenhorst’s Algen Europa’s, 
No. 2492.—Sc. Chrysochlorum, Ktz., Niagara, shaded rocks.—Sc. 
natans, Breb. In pools. 
18. Symphyosiphon, Ktz.—S. incrustans, Ktz.—S. Contarenii, 
Ktz. Both common on rocks exposed to the spray of Niagara Falls. 
S. Wolle’, Bornet, m. sp. Forms a more or less expanded stratum, 
one line .high, on calcareous rocks. Olive black, ascending, 
curved, sparsely branched, single or geminate patent. ‘l'richoma con- 
tinuous, or indistinctly articulate; articles equal to or less than diam- 
eter, rarely submoniliform, towards the ends two or three divisions to 
diameter, often distinct, dull aeruginous or olive-yellow, granular, 
not enlarged at the ends. Sheath firm, smooth and usually very 
close. Ends rounded but often open and colorless. Heterocysts sub- 
globose or nearly square. Vag. .0006”—.00081”. | 
- 1g. Tolypothrix, Ktz.—T. muscicola, Ktz. Pond mosses.—T. 
truncicola, Thuret, moist wood. 
20. Plectonema, Thuret—PI. mirabile, Thuret. On wood and 
moss in lime stone springs.—PI. Wollei, Farlow. For description, see 
Bulletin of Bussey Institution, Vol. IL, part 1., p. 75. Attached to 
stones and sticks in slow waters. 
21. Fischera, Schwabe.—F. thermalis, Schwabe. Differs from 
the European form in having the trichoma more than one-third 
thicker. In small pools in swampy ground. 
_ 22. Pleurococcas, Menegh.—PI. minuatus, Ktz.—Pl. vulgaris, 
Menegh. | é 
23. Gloeocystis, Naeg.—Gl. rupestris, Lyngh. Calcareous rocks 
in a cave. 
