34 WISCONSIN PHYTOPLANKTON 



KEY TO THE SPECIES. 



Cells spherical. 



Diameter of cells not exceeding 4 /JL C. KUETZINGIAUM: 



Diameter of cells over 5 ^ C. DUBIUM 



Cells ovoid to ellipsoid C. NAEGELIANUM 



COELOSPHAERIUM KuETziNGiANUM Nageli. PI. 3, Figs. 4-5. 

 Gatt. einz. Algen 54, pi. 1, fig. C. 1849. 



Colonies spherical to subspherical, enclosed by a very hyaline, homo- 

 geneous, gelatinous envelope. Cells spherical to subspherical, forming 

 a single layer, with the individual cells or pairs of cells some distance 

 from one another or close together. Cell contents homogeneous, with- 

 out pseudovacuoles ; usually grey to pale blue-green, rarely bright blue- 

 green. (Facultative planktont). 



Diam. cells 2.25-4 ^ ; diam. colonies 20-90 //.. 



Balsam (IT), Bass (2) (rr), Bear (3) (r), Bear Trap (rrr), Beaverdam (ss), 

 Big (ss), Big Butternut (sss), Birch Island (rrr), Blake (ss), Bone (rr), 

 Browns (rr), Carson (r), Catfish (r), Clam (ss), Cochrane (sss), Crab (rr), 

 Cranberry (ss), Crawling Stone (sss), Deer (rr), Diamond (rrr), Elizabeth 

 (s), Eagle (ss), Fence (sss), Fish (rr), Grindstone (rr), Green (2) (rr), Half 

 Moon (r), High (sss), Hillman (ss), Horseshoe (1) (rrr), Kegonsa (s), Kit- 

 ten (rr), Island (ss), Lac la Belle (rr), Lindy (rr), Little Bear (rrr), Little 

 Butternut (r), Little Crooked (rr), Little Rice (1) (ss), Little Yv T ood (s), 

 Long (2) (rr), Long (3) (rr), Loveless (sss), Mary (s), Mendota (s), Mer- 

 cer (rrr), Mill (rrr), Mud (1) (cc), Mud (2) (r), Mudhen (s), Nancy (rrr), 

 Nicaboyne (rr), North Turtle (ss), Oconomowoc (r), Owen (rrr), Paddock 

 (ss), Palmer (ss), Pardee (cc), Pewaukee (rr), Pine (2) (rr), Pine Tree (rr), 

 Pokegama (1) (sss), Pokegama (2) (r), Pokegama (3) (rrr), Poplar (ss), 

 Reserve (ss), Rice (1) (rr), Rock (sss), Round (3) (sss), Sand (1) (rr). 

 Sand (3) (rr), Sand (4) (r), Silver (1) (ccc), Silver (2) (ss), South Turtle 

 (ss), Spirit (ss), Sunday (r), Tamarack (rr), Tenderfoot (sss), Tied Canoe 

 (rrr), Upper Nemahbin (rrr), Upper Turtle (sss), White Ash (sss), White- 

 fish (s), White Sand (sss), Wildcat (rr), Wild Goose (rr), Winnebago (rr), 

 Wolf (r). 



The gelatinous sheath is generally so delicate that it is necessary to 

 use Errera's method of mounting colonies in dilute India ink to demon- 

 strate its presence. The specific limits of this species as established 

 by different authors frequently includes C. Naegelianum as a synonym. 

 C Kuetzingianum and (7. Naegelianum are two well defined species that 

 differ in colony shape, cell shape, occurrence of pseudovacuoles, struc- 

 ture of colonial envelope, and relative abundance. C. Kuetzingianum 

 is a species that is widely distributed throughout the state but one which 

 rarely becomes a dominant member of the plankton and never occnrs 

 in sufficient abundance to cause blooming. 



