WISCONSIN PHTTOPLANETON 



OOCYSTIS PANDURIFORMIS var. MINOR G. M. Smith. PI. 23, Fig. 3. 

 Bull. Torr. Bot. Cl. 43: 471, pi. 24, fig. 2. 1916. 



Cells oblong-ovoid, 2 to 2y 2 times as long as broad, sides slightly 

 concave and poles with a conspicuous nodule. Chloroplasts numerous 

 (15-25), parietal, disciform, and each containing a pyrenoid. Cells 

 solitary or in families of 2-4-8. (Tychoplanktont). 



Greatest diameter of cells 12-15 p., median diameter 11-14; length 

 30-35 p. 



Star (rr). 



This is the only species of the genus where the sides of the cells are 

 concave. 



Oocystis natans var. major var. nov. PI. 23, Figs. 4-5< 



Cells ovoid, without a conspicuous polar nodule. Chloroplasts 4-8, 

 parietal, star-shaped or irregular, each chloroplast with a pyrenoid. 

 More than two cell generations rarely found within the same mother 

 cell wall. (Facultative Planktont). 



Cells 16-25 /* broad, 31-38 /* long. Families up to 90x120 /*. 



Birch (2) (sss), Chetac (s), Rice (1) (rr). 



Lemmermann founded the genus Oocystella upon this stellate nature 

 of the chloroplast (Zeits. f. Fischeri u. d. Hilfsw. 11: 103. 1903) but 

 the genus has not been recognized and the single species is placed in 

 Oocystis. 



NEPHROCYTIUM Nageli 1849. 



Cells ovoid, reniform, or oblong-elliptic; generally in colonies of 

 2-48-16 cells within the partially gelatinized remains of the old mother 

 cell wall. Arrangement of cells in young colonies spiral, in old colonies 

 irregular. Chloroplast single and expanded at first, later fragmenting 

 and becoming diffuse ; pyrenoid single. 



Reproduction by the formation of 2-4-8-16 autospores in each cell. 



NEPHROCYTIUM AGARDHIANUM Nageli. PI. 23, Figs. 6-7. 

 Gatt. einz. Algen 79, pi. 3, figs. Ca-CP. 1849. 



Cells reniform, generally spirally arranged in young colonies. Chlor- 

 oplast single, parietal, laminate, and with one pyrenoid in young cells ; 

 diffuse in old cells. (Tychoplanktont). 



Cells 2-12 fi broad, 6-28 /t long ; colonies up to 60 p. long. 



Bear (3) (rrr), Bear Trap (rrr), Camp (rr), Hillman (rr), Little Bass 

 (rrr), Mendota (rr), Mill (rrr). 



