188 NEMATOPHYCES. 
Famity VIII. CHASTOPHORACEA. 
Aquatic or swamp-living alge, rarely terrestrial, monecious 
or diceecious. Articulate filaments various, often dichotomously 
branched, not rarely fasciculately branched, accumulated in 
tufts or pulvinules, nestling in a somewhat fluid or firm gela- 
tinous mucus, or constituting, for the most part, a filamentose, 
rarely a somewhat foliaceous thallus (formed from a single 
stratum). 
Propagation by oospores after sexual fecundation, or by zoo- 
gonidia ; the latter produced singly, or by the division of the 
cytioplasm, or contents of the sporangium, into eight or sixteen. 
Genus 70. MICROTHAMNION. Jag. (1849.) 
Articulate filament dichotomously or trichotomonsly branched, 
now and then very much branched, straight, with the terminal 
cell obtuse, or nearly so, afterwards swollen, forming a sporan- 
gium. Cell contents effused, containing scattered amylaceous 
granules. Propagation by zoogonidia. Plants microscopical, 
more or less with a gelatinous investment. 
Microthamnion vexator. Cke. in Grevillea xt, p. 75. 
Filaments erect, very slender, dichotomously branched, more 
or less growing in tufts. Cells cylindrical, longer than broad, 
not at all constricted at the joints, dissepiments scarcely visible. 
Cell membrane thin, pellucid. 
Size. Cells about 003 mm. diam. 
Attached to aquatic plants in clear springs, &c. 
A very delicate plant, first found by Mr. Turner in Yorkshire, and 
since detected in several localities in England. Very much more slender 
than M. strictissimum. 
Plate LXXIII. fig 1. Filaments of Microthamnion vexator X 400. 
a, tafts of plants natural size, 
Genus 71. STIGEOCLONIUM. Kutz. (1843.) 
Articulate threads simply branched, branches and branchlets 
scattered, rarely approximate in a fasciculate manner, acute at 
the apex, sometimes attenuated into a colourless bristle, at times 
extended very long, at other times furnished with shortly 
subulate branches. Cell membrane very thin and hyaline, homo- 
geneous, Cell contents. with the chlorophyll arranged in 
transverse bands. 
