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Phormidium, Ktz.—P. Retzii, Ktz—P. Naveanum, Grun.—P. 
subtorulosum, Breb.—P. fonticola, Ktz.—P. Julianum, Rabenh. 
Allfrom Florida. Coll. J. D. Smith.—P. fasciculatum, Naeg.— 
P. Joannianum, Ktz. Both from Suffern, N. Y. The first 
growing on Aulocomnium in a swamp; the other from old wood. 
Coll. C. F. Austin.—P. rupestre, Ag. Forms a matted stratum 
on rocks; Garrett Co., Md., Coll. J. D. Smith. 
Lyngbya, Ag.—L. aeruginosa, Ag. In pools of moist earth subject 
to inundations from flowing tides, N. Jersey.—L. major, Ktz. 
St. Lucia river, Florida. Coll. J. D. Smith. 
Hydrocoleum, Ktz.—H. heterotrichum, Ktz.—H. Helveticum, Naeg. 
In gelatinous strata on stones in marshy places. 
Symploca, Ktz.—S. fuscescens, Ktz.—S. terrestris, Ktz. Wet 
ground and river banks. 
Nostoc, Vauch.—N. muscorum, Ag. On Grimmia. Coll. T. S. Bran- 
degee, Colorado’ A dubious species and genus. 
Nostochopsis, Wood. Have plants from Florida that agree well 
with diagnosis. They are probably an undeveloped form of 
Hapalosiphon. Coll. J. D. Smith. 
Capsosira, Ktz.—C. Brebissonii, Ktz. Intermingled with Phormid- 
tum. Florida. Coll. J. D. Smith. 
Mastigonema, Swabe——M. Donnellit, n. sp.—M. caespitosum in 
strato mucoso, olivaceo-viridi; filamentis saepius simplicibus, 
flagelliformibus, longissime productis, variis, modo tenuibus et 
flaccidis, modo validis et rigidis, diametro .00024""—.0005”, 
ad basim saepe .0006”—ooo08”, nonnumquam pseudo-ramosis, 
leniter curvatis, dense intricatis; internis pallide vel pulchre 
aerugineis, vel fuscescentibus, saepe interruptis; distinctis- 
sime sed breviter articulatis ; articulis diametro plerumque 4-5- 
plo brevioribus ; arctissime vaginatis ; vaginis achrois subtil- 
issimis, in apice saepe filiforme productis; adultis truncatis et 
apertis. Cellulis perdurantibus, globosis, compressis, basalibus 
et rarius interstitialibus. Hab. in lignis aqua maritima sub- 
mersis. 
This is a beautiful plant, but variable, and might under 
some of its transformations be classified with the Lezd/einia, 
Endl, or Desmarestella, Bory, but the basal heterocysts of the 
perfect plants, the formation of spores in the swollen basal 
parts of the trichomas and the development of the plants from 
subspherical spores, all of which I found fully exemplified, 
connect it with the Mastigonemas. Filaments are some- 
times thin and flaccid, but the bases are much swollen. Inter- 
mingled are others of twice the size. The articulations are 
composed of thin disks; these frequently separate into short 
sections, the disks of the ends of which incline towards each 
other, and thus form a sort of dark double concave division 
in the trichomas, such as are not unfrequently seen in the fila- 
ments of Lyngbya, Tolypothrix, etc. 
M. velutinum, n. sp.—M. strato plus minus expanso ad 
duas lineas crasso, pulvinato, humectato molli-tomentoso, 
velutino, saturate olivaceo-viridi ; trichomatibus subrectis vel 
