. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . g. In Westella and Protococcacex 191 Diuiorphococcus (tig. 117) there is comparativelystanding the free-floating nature of the colonies,and the relics of the mother-cell-walls, which areto a great extent very irregular, are thereforeof great importance as binding-threads. In allexcept Dictyosphierium Hitcltcockii the chloro-plast is parietal, often very massive, and withor without a pyrenoid. Multiplication takes place by the formationof four
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . g. In Westella and Protococcacex 191 Diuiorphococcus (tig. 117) there is comparativelystanding the free-floating nature of the colonies,and the relics of the mother-cell-walls, which areto a great extent very irregular, are thereforeof great importance as binding-threads. In allexcept Dictyosphierium Hitcltcockii the chloro-plast is parietal, often very massive, and withor without a pyrenoid. Multiplication takes place by the formationof four daughter-cells (sometimes only two inDictyosph&rium) within the mother-cell. Thedivision-planes are oblique; in Westella thefour daughter-cells are always arranged in oneplane, but in Radiococcus they are tetrahe-drally disposed. The colonies frequently disso-ciate, each group of four cells being thecommencement of a new colony. Reproductionby biciliated zoogonidia has been observed inDictyosphxrium by both Zopf and Massee, butdoes not occur under normal circumstances, norhas it been observed in any of the other genera. little mucus, notwith-. Fig. 117. Dimorphococcus lunatusA. Br. x520. In A one cellshows division of contents ofmother-cell into four daughter-cells. The family may be conveniently divided as follows : Sub-family DICTYOSPHJBRIE^; : Colonies completely enveloped in mucus ; cells in groupsof two or four. Dictyosph&rium Nageli, 1849 [inclus. Dictyocystis Lagerheim, 1890];Radiococcus Schmidlc, 1902. Sub-family QUATERNAT/E : Colonies with very little surrounding mucus; cells indefinite groups of four more or less in one plane. Dimorpltococcus A. Braun, 1849 [ Bernard, 1908]; Westella De Wildeman (in part) [Telmcoccus W. West, 1892 J. Family Protococcaceae. This family as here constituted is the Pleurococcacese of most cells are for the most part aggregated to form a definite stratum, butthey may be scattered as unicells among other
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