. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . D Fig. 255. Stipitococcus urceolatus W. &G. S. West. A—C, epiphytic on afilament of Mougeotia; D, epiphytic011 Sphserozosma excavatum. A andD, x500; B and C, x 780. Botnjococcacese 405 Isogametes occur in Misckococcus, in which genus the zygospore ongermination divides in two directions in one plane, forming an epiphyticcushion, all the cells of which are situated on short, broad, mucilaginousstalks. This condition might almost be regarded as
. Algæ. Vol. I. Myxophyceæ, Peridinieæ, Bacillarieæ, Chlorophyceæ, together with a brief summary of the occurrence and distribution of freshwat4er Algæ . D Fig. 255. Stipitococcus urceolatus W. &G. S. West. A—C, epiphytic on afilament of Mougeotia; D, epiphytic011 Sphserozosma excavatum. A andD, x500; B and C, x 780. Botnjococcacese 405 Isogametes occur in Misckococcus, in which genus the zygospore ongermination divides in two directions in one plane, forming an epiphyticcushion, all the cells of which are situated on short, broad, mucilaginousstalks. This condition might almost be regarded as a palmella-state. The genera are: Peroniella Gobi, 1887 ; Stipitococcus W. & G. S. West, 1898 ;Mischococcus Niigeli, 1849 ; Chlorosaccus Luther, 1898 ; Racovitziella De Wildeman, 1900[ = Tetrasporopsis Lerumerinann & Sclnnidle (according to Wille); DictyosphxropsisSchmidle, 1903]. Peroniella and Stipitococcus might be compared with Physocytium among the Palmellacese,and similarly a comparison might be instituted between Misckococcus and Fig. 256. Mischococcus confervicola Nag. A, entire colony; B and C, parts of other xf>00. Family Botryococcacese. It is highly probable that the Botryococcacese form a natural family andthe genera included in it seem to belong to the Heterokontae rather than tothe Isokontse. All the forms are colonial, the smallest colonies being those ofStichoglcea and the largest those of Botryococcus. The colonies are, as a rule,free-floating and they may occur in great numbers in the freshwater Stichogloea they usually consist of four or eight cells, enveloped in abundantbut rather indistinct mucilage, each group of four cells being disposed ina somewhat irregular cruciform manner, and the poles of the cells beingconnected by firmer and thicker mucilaginous strands. There are two parietalchromatophores in each cell. A less-known genus is Askenasyellct in whichthe colonies, although larger than in Stichogl
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