WISCONSIN PHYTOPLANKTON 29 



CHROOCOCCUS LIMNETICUS Lemmermann. PI. 1, Fig. 4. 



Bot. Cent. 76: 153. 1898; Forschungsbr. a. d. Biol. Stat. zu Pl6n 7: 132, pi. 1, 

 figs. 22-23. 1899. 



Mature cells spherical to subspherical, 4-32 in a free-floating spheri- 

 cal to ovoid colony. Cells fairly close together and equidistant from 

 one another within the colony, sometimes in groups of 2-4 but with 

 the groups lying close together. Cell division in all three planes but 

 a majority of the cells dividing in the same plane and giving the colony 

 a somewhat tabular appearance. Many hemispherical cells present be- 

 cause of the slow maturation after division. Individual cell sheaths 

 homogeneous and frequently confluent with colonial envelope. Cell 

 contents homogeneous ; grey, pale to bright blue-green, or olive-green. 

 ( Euplanktont) . 



Diam. cells (without sheath) 6-12 //,, (with sheath) 8-14 /t. 



Balsam (r), Bear (1) (rr), Bear (2) (rrr), Bear Trap (sss), Beasley (rr), 

 Beaver (1) (r), Beaver (2) (ss), Big Butternut (r), Birch (1) (rr), Birch (2) 

 (SB), Birch Island (s), Blake (sss), Bloom (s), Boulder (rrr), Browns (s), 

 Camp (rr), Catfish (rr), Chetac (r), Chetek (rrr), Cranberry (sss), Dunham 

 (rr), Dutchmans (r), Eagle (rr), East (rr), Fish (rr), Found (rr), Fowler 

 (rr), Grassy (rr), Grindstone (rr), Half Moon (rr), Horseshoe (1) (r), 

 Island (rr), Kawaguesaga (rr), Kimball (rr), Lac Court Oreilles (rr), Lac la 

 Belle (r), Little Bass (2) (ss), Little Butternut (rr), Little Rice (2) (rr), 

 Little Wood (sss), Loveless (r), Mary (rr), Middle McKenzie (r), Mill (rr), 

 Mud (1) (rr), Mud (2) (rr), Mudhen (r), Nicaboyne (r), North Twin (rr), 

 Oconomowoc (rr), Old Taylors (rr), Pewaukee (rr), Pike (rr), Pine Tree (rr), 

 Pokegama (1) (r), Pokegama (2) (rrr), Pokegama (3) (rr), Poor Farm (rr), 

 Poplar (ss), Reserve (sss), Rice (1) (r), Round (3) (rr), Sand (1) (s), 

 Sand (3) (sss), Sand (4) (rr), Shell (sss), Silver (2) (r), Spirit (r), Squir- 

 rel (r), Tenderfoot (rrr), Travis (rrr), Upper Nashotah (rr), Upper Nemah- 

 bin (rr), White Ash (ss), Whitefish (s), Wildcat (rr), Wlnnebago (r), Wolf 

 (rr). 



This is preeminently a plankton species. It is widely distributed 

 throughout the state and may be the dominant member of the Myxo- 

 phyceae in lakes with very soft water, but it never occurs in sufficient 

 abundance to cause the familiar phenomenon of blooming. The cells 

 are quite variable in both color and size. 



var. SUBSALSUS Lemmermann. PI. 1, Fig. 5. 



Forschungsbr. a. d. Biol. Stat. zu P16n 8: 84. 1901; Arkiv f. Botanik 2: No. 2: 

 101, pi. 1, fig. 9. 1904. 



Cells spherical to subspherical, 8-16-32 in a somewhat spherical or 

 broadly ellipsoidal colony with a wide gelatinous envelope. Cell con- 

 tents homogeneous; pale to bright blue-green. (Euplanktont). 



