188 NEMATOJPHYCE^. 



FAMILY VIII. CH^ETOPHORACBJB. 



Aquatic or swamp-living algaa, rarely terrestrial, monoecious 

 or dioecious. 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. MIC ROTH AMNION. Nag. (1849.) 



Articulate filament dichotomously or trichotomously 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 xi., 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,*aud 

 since detected in several localities in England. Very much more slender 

 than M. strictissimum* 



Plate LXXIII. fy 1. Filaments of Microthamnion vexator X 400. 

 #, tufts 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. 



