WISCONSIN PHYTOPLANKTON 67 



CHRYSAMOEBA Klebs 1893. 



Cells solitary, free-floating, with a mono-flagellate motile phase and 

 an amoeboid non-motile phase. Motile phase broadly ovoid, naked, 

 with two elongate, laminate, golden-brown chromatophores ; a large 

 non-contractile vacuole, 2-3 small contractile vacuoles; and a single 

 flagellurn slightly longer than the cell. Eye-spot lacking. 



Non-motile phase solitary or in small clumps, with several simple or 

 branching pseudopodial processes extending in all directions. Chro- 

 matophores and vacuoles as in the motile phase. 



CHRYSAMOEBA RADIANS Klebs. PI. 12, Fig. 1. 

 Zeits. f. wiss. Zool. 55: 406, pi. IS, figs, la-lb. 1893. 



Specific characters as described above. (Euplanktont). 

 Motile phase 8-10 ^ broad, 12-15 /*, long; amoeboid phase (without 

 processes) 12-17 p. broad, (with processes) 35-40 /u, broad. 



Round (4) (rr), Taylor (rr). 



Family MALLOMONADACEAE. 



Cells always free-swimming, solitary or colonial, never metamorphos- 

 ing into a palmella or rhizopodial phase. Periplast of cells or colonial 

 envelope with numerous small plates of silica that have long, siliceous, 

 needle-like processes. Cells ovoid to ellipsoid, with one flagellum, a 

 number of contractile vacuoles and two long laminate chromatophores. 



/ 



KEY TO THE GENERA. 



Cells solitary MAIXOMONAS 



Cells in spherical colonies CHBYSOSPHAEKELLA 



MALLOMONAS Perty 1852. 



Cells always solitary, free-swimming, with a single flagellum at the 

 anterior end. Periplast of cells with small circular or angular siliceous 

 discs covering the entire surface of the cell or restricted to one or both 

 ends. Scales frequently arranged in regular transverse or diagonal 

 rows, produced into a single, long, simple or toothed, needle-like setae. 

 Cells containing one or more contractile vacuoles that may be apical, 

 median, or basal in position. Chromatophores two, parietal, laminate, 

 and golden-brown in color. Assimilation product leucosin. 



Reproduction by vegetative cell division parallel to the long axis. 

 Akinetes known in many species. 



