Planktosphaeria gelatinosa G. M, Smith 1918, p. 627 



PI. 53, Fig. 23 



Characteristics as described for the genus; cells (4.5)-20-25ju in 

 diameter. 



This plant should be compared with Sphaerocystis Schroeteri, 

 which has a single parietal, cup-shaped chloroplast and in which 

 the cells are usually more distantly arranged. In old colonies of 

 Planktosphaeria gelatinosa the cells may become somewhat loosely 

 arranged, but usually they are closely clustered. 



Common in the plankton of a variety of lakes and ponds, both in 

 hard and soft water. Mich., Wis. 



EREMOSPHAERA DeBary 1858, p. 56 

 Cells spherical, spheroidal, or somewhat angular-spheroidal (3- 

 angled in face view ) ; solitary or 2-4 together within an old mother 

 cell wall, with or without a gelatinous sheath; free-floating or lying 

 among mixtures of algae in shallow water; chloroplasts numerous, 

 ovate or irregularly shaped discs or pads, with large starch grains, 

 lying in a meshwork along the periphery or in radiating strands of 

 cytoplasm from a central core which involves the nucleus. The 

 chloroplasts are able to shift their position in response to light 

 stimulus. 



Key to the Species 



Cells spheroidal or angular-spheroidal, 2-4 within an old mother 



cell wall, inclosed by a gelatinous sheath E. oocystoides 



Cells spherical, sohtary, sheaths not apparent— E. viridis 



Eremosphaera oocystoides Prescott in Prescott, 

 Silva & Wade 1949, p. 85 

 PI. 46, Fig. 12 

 Cells spheroidal or triangular-spheroidal in one view, 2-4 (rarely 

 solitary) within old mother cell walls which are ovate or oblate- 

 spheroidal, inclosed in a wide gelatinous sheath in which there are 

 numerous radiating spicules, the old mother cell wall often appear- 

 ing spiny, and showing flattened, thickened poles; chloroplasts 

 numerous, small irregularly shaped plates, lumpy with starch grains; 

 cells up to 122/x in diameter; colony 300-450^^ in diameter. 

 In shallow water of an acid swamp. Mich. 



Eremosphaera viridis DeBary 1858, p. 56 

 PI. 53, Fig. 22 

 Cells solitary, spherical, not inclosed by a mucilaginous sheath; 

 chloroplasts as described for the genus; cells 50-350/x in diameter. 



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