4. Cells epiphytic, on the mucilage of Microcystis C. epiphytica 



4. Cells not epiphytic on colonies of Microcystis 5 



5. Cells globose, with 2 contractile vacuoles in 



the anterior end _._,. C. pseudopertyi 



5. Cells ellipsoid or ovate 6 



6. Papilla sharply pointed C. Snowii 



6. Papilla broad and truncate; cell often truncate 



and angular at the anterior end C. angulosa 



7. Cells with 2 apical papillae C. sphagnicola 



7. Cells without papillae, or with only 1 8 



8. Cells ellipsoid, with 1 pyrenoid C mucicola 



8. Cells ovate or cylindrical, with many pyrenoids- 9 



9. Cells ovoid, without a papilla; pyrenoids 



many (12-16), lateral C. pohjpyrenoideum 



9. Cells cylindrical to subcylindrical, with a papilla; 



pyrenoids few C. Cienkowskii 



Chlamijdomonas angulosa Dill 1895, p. 337 



PI. 1, Fig. 3 



Cells broadly ovoid to cylindric, often truncated anteriorly and 

 with a prominent papilla. Contractile vacuoles 2, below the flagella, 

 which are as long as or slightly longer than the cell body. Chloro- 

 plast a massive, parietal cup with a large angular pyrenoid in the 

 base; pigment-spot anterior and lateral. Cells 11-13- (15) /a in dia- 

 meter, 15-18-20/A long. 



Tychoplankter. Wis. 



Chlamydomonas Cienkowskii Schmidle 1903a, p. 349 



PI. 1, Fig. 4 



Cells cylindric to subcylindric with a prominent apical papilla, 

 below which are 2 contractile vacuoles. Flagella shorter than the cell 

 in length. Chloroplast a thin, parietal, cylindrical cup with several, 

 pyrenoids. Pigment-spot anterior and lateral. Cells 10-11//, in dia- 

 meter, 20-25f(, long. 



Our specimens are shorter than usual for this species, but the shape 

 of the cell, the form of the chloroplast, and the number of pyrenoids 

 are in agreement. 



Tychoplankter. Wis. 



Chlamydomonas Dinobryonii G. M. Smith 1920, p. 91 



PL 1, Fig. 5 

 Cells ovoid to pyriform, without an anterior papilla, inhabiting the 

 empty loricas of Dinobryon; flagella G-Sju, long. Chloroplast disc- 



[70] 



