WISCONSIN PHYTOPLANKTON 71 



KEY TO THE FAMILIES. 



Cells naked, at times in a gelatinous envelope but never a 



definite receptacle OCHEOMONADACEAB 



Cells within a definite receptacle DINOBRYACEAB 



Family OCHROMONADACEAE. 



Cells solitary or in colonies, always free-swimming, not enclosed by 

 a definite receptacle but at times with a hyaline, homogeneous, gelat- 

 inous envelope. Cells with two apical cilia of unequal length, one or 

 two golden-brown chromatophores, an eyespot and contractile vacuoles. 



Uroglenopsis is the only representative in the local flora. 



UROGLENOPSIS Lemmermann 1899. 



Colonies free-swimming, with the cells embedded in a single layer at 

 the periphery of a copious, hyaline, homogeneous, gelatinous matrix of 

 spherical to broadly ellipsoid shape. Arrangement of cells radial or 

 somewhat irregular. Cells spherical to narrowly ellipsoid; with two 

 cilia of unequal length; two vacuoles at the anterior end; one or two 

 laminate to discif orm, parietal, golden-brown chromatophores ; and with 

 or without an eyespot. 



Eeproduction by vegetative cell division. 



UROGLENOPSIS AMERICANA (Calkins) Lemmermann. PI. 13, Figs. 1-4. 



Forschungsbr. a. d. Biol. Stat. zu Plon 7: 107. 1899; Kryptogamenfl. d. Mark 

 Brandenburg 3, Algen 1: 449, 444, figs. 1-3, 4-6. 1908. 



Uroglena americana Calkins, Ann. Rept. Mass. State. Bd. of Health 23: 655, 

 pi. 4, figs. 1-4. 1892; Moore, Bot. Gaz. 23; 105, pi. 10, figs. 1-11. 1897. 



Colonies free-swimming, generally spherical. Cells ellipsoid, with 

 one basal or lateral, parietal, discif orm to laminate chromatophore. Eye- 

 spot single. Cilia of unequal length, with the longer 2-3 times the 

 length of the cell, the shorter %-V 2 the length of the cell. (Euplank- 

 tont). 



Cells 3-7 p. broad, 5-10 /* long. Colonies up to 500 /*, in diam. 



Beasley (cc), Bettine (ss), Browns (ss), Camp (ss), Carson (rrr), Diamond 

 (rr), Eagle (sss), Fowler (cc), Howey (rr), Lac la Belle (ss), Long (3) (ss), 

 Long (4) (rr), Lower Nemahbin (rr), Lynx (rr), Mendota (ss), Mill (ss), 

 Mud (4) (cc), Nancy (rr), Oconomowoc (ss), Okauchee (rrr), Otter (ss), 

 Paddock (s), Pewaukee (rr), Rainbow (1) (ss), Round (4) (rr), Taylor (ss), 

 Wildcat (ss), Wolf (rr), Youngs (cc). 



