jj. With a gelatinous cover, 

 k. Colon}' ovate or spherical. 



I. Cells 16-32, globose, not crowded (figs. 7, 8) Eudorina. 



II. Cells 8, 16, 32, or 64 globose, crowded, (figs. 13, 16). 



Pandorina. 



kk. Colon}' of 8 cells in an equatorial zone in a spherical or 



ellipsoidal investment. Stephanosphccra. 



ii. Colonies flat, cells 4-16, angles rounded, in a colorless sheath 



(Compare also Uvella fig. 14). (fig. 10). Goftium. 



hh. Composed of single cells with two, or rarely four cilia. 



i. Contents of cell close to cell wall (fig. 4). Chlainydonionas. 



ii. Contents of cell connected with cell wall by threads (fig. 2). 



Sphccrella. 

 gg. Cells not ciliated or motile. (See illustration II). 

 h. Cells formed in flat plates or in a net work. Hydrodictvace^. 

 i. Cells in a flat plate (fig. 1,2). Pediastruni. 



ii. Cells form a net work (fig. 25). Hydrodidyon. 



hh. Cells not in a plate or network, 

 i. Unicellular and solitary ; cell with differentiation of base and 

 apex (fig. 5). CharaciacE-E. Characiicm. 



ii. Cells without differentiation of base and apex, 

 j. Unicellular and globular or consisting of short, few celled fila- 

 ments ; firm cell wall. Often in damp situations (figs. 22, 

 23). Pi^EUROCOccACE.^. Pleurococcus. 



jj. Not as above, 

 k. Cells spherical and indefinite in niimber, embedded in a 

 copious gelatinous envelope (fig. 21). 



PalmellacE-E. Tetraspora, et al. 



kk. Cells free or colonial, without copious gelatinous envelope ; 



forming autospores. ProtococcacE-^. 



I. Cells elongated, frequently curved ; solitary or in definite 



loosely coherent colonies, 

 m. Colonies enveloped in mucus (fig. 3). Kirchneriella. 



mm. Colonies with little or no mucus, 

 n. Cells attenuated to acute spines. 

 o. Cells forming definite colonies each of a single row. 

 (fig. 14). Scenodesuius. 



00. Cells solitary or loosely grouped in irregular bundles 

 (figs. II, 12). Ankisfrodesniiis. 



000. Cells lunate, arranged back to back, (fig. 7). 



Selenastruni. 



nn. Cells sublunate or ellipsoidal, arranged in groups forming 



irregular colonies. Dimorphococcus. 



II. Cells not elongated. 



m. Cells variable, united in a regular flat plate (fig. 26). 



Crucigenia. 

 mm. Cells not united in a flat plate, 

 n. Cells angular, with a definite number of angles, two, four, 

 six, eight, or more ; cells solitary. Tetraedron. 



