. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . uddy of both genera may also be epiphytic on larger Algse. 1 From the remarks of Hazen (02) it would appear that this genus should rightly beregarded as a synonym of Hormiscia Fries, 1835. Rhizoclonieae 267 Sub-family RHIZOCLONIE^:. The filamentous thallus of these Algse isbranched, or less frequently unbranched. There is, as a rule, a basal rhizoidalattachment (fig. 171 F and G). In Spongomorpha the branching is consider-able,
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . uddy of both genera may also be epiphytic on larger Algse. 1 From the remarks of Hazen (02) it would appear that this genus should rightly beregarded as a synonym of Hormiscia Fries, 1835. Rhizoclonieae 267 Sub-family RHIZOCLONIE^:. The filamentous thallus of these Algse isbranched, or less frequently unbranched. There is, as a rule, a basal rhizoidalattachment (fig. 171 F and G). In Spongomorpha the branching is consider-able, but in Rhizodonium the branches are generally short, often attenuated,and sometimes reduced to unseptate outgrowths (fig. 171 B). The filamentsare usually slightly bent and twisted owing to the uneven growth of theindividual segments, which are themselves in many cases asymmetrical, andin the vicinity of the branches not infrequently irregular (fig. 171 C). Thecell-walls are strong and firm, sometimes conspicuously lamellose, and theymay attain a great thickness, as in Rhizodonium profundum and the subaerialspecies R. crassipellitum (fig. 171 E).. Fig. 171. A— C, parts of filaments of Khizoclonium Berggrenianum Hauck var. DominicenseW. & G. S. West, with short lateral branches, x 450. D, single cell of E. hieroglyphicumKiitz. to show reticulate chloroplast and pyrenoids (py). E—G, R. crassipellitum W. &G. S. West, a terrestrial species; E, showing great thickness of lamellose wall, x450;F and G, bases of two filaments with rhizoidal outgrowth (•;•), x 105. The nuclei of the segments are greatly reduced in numbers in this sub-family, only two being present in some species of Rhizodonium and inSpongomorpha only one. The chloroplast forms a parietal network in thethicker parts of which pyrenoids are located (fig. 171 D). The reticulationis probably brought about as in Cladophora by the fusion of the producedangles of numerous small plates, each with a pyrenoid. It i
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