with a few small sharp spines; chromatophores 2 lateral, plate-like 

 bodies, one on either side of the cell; 2 flagella of equal length; 

 cells 8-10/A in diameter, 40-45/x long. 



This species appears to be synonymous with S. uvella var. longipes 

 Virieux (1916, p. 76). 



Rare in the plankton of a few lakes and swamps. Wis. 



Synura uvella Ehrenberg 1838, p. 61 

 PI. 92, Figs. 6,7 



A free-swimming colony of 64-128 short pyriform cells which have 

 several short, sharp spines in the anterior region of the wall; cells 

 8-11 IX in diameter, 20-30- ( 35 )/x long. 



Not infrequently this species becomes superabundant and pro- 

 duces the equivalent of a water bloom. In lakes and reservoirs this 

 organism may become obnoxious because of the stiong oily taste it 

 imparts to drinking water. 



Common in the plankton of many lakes, especially in hard water 

 and in habitats where there is a high concentration of organic 

 matter. Mich., Wis. 



Suborder Ochromonadineae 



These organisms are either solitary or colonial and swim by means 

 of 2 flagella of unequal length. Only one of the famihes is repre- 

 sented in our region. 



FAMILY OCHROMONADACEAE 



Organisms with a smooth, undecorated cell membrane; colonial 

 or solitary cells sometimes inclosed in a lorica of definite shape. 

 ( See other characteristics in the description of the order. ) 



Key to the Genera 



1. Cells inclosed by a lorica of definite shape; 



solitary or in arbuscular colonies — 2 



1. Cells not inclosed in a lorica, arranged in 



spherical, free-swimming colonies Uroglenopsis 



2. Lorica conical, with transverse growth scars 



which form lateral bristles Hyalobnjon 



2. Lorica conical or cylindrical throughout most of its length; 



without transverse growth scars Dinobryon 



DINOBRYON Ehrenberg 1835, p. 279 

 Free-swimming or attached; rarely sohtary, usually forming arbor- 

 escent colonies of conical or vase-like loricas, each inclosing a single, 

 ovoid or spindle-shaped, pigmented protoplast which is attached by 



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