90 WISCONSIN PHYTOPLANKTON 



Family CHLAMYDOHONADACEAE. 



Cells normally solitary and motile during the vegetative phases of 

 the life history. Spherical, ovoid, cylindrical, sub-acicular, compressed, 

 or quadrately projected. Chloroplast cup-shaped to laminate, lateral 

 or posterior in position, with or without pyrenoids. Cells uninucleate, 

 with or without an eyespot, with two cilia of equal length that generally 

 have two contractile vacuoles at their base. Cells at times becoming 

 immobile and developing into amorphous colonies enclosed by a wide 

 gelatinous envelope. 



Asexual reproduction by the division of cell contents to form 2-16 

 biciliate zoogametes. 



Sexual reproduction by the fusion of isogamous zoogametes. 



CHLAMYDOMONAS Ehrenberg 1832. 



Cells normally solitary and motile ; though capable of coming to rest, 

 losing the cilia, developing a gelatinous envelope and dividing vegeta- 

 tively to form colonies containing an indefinite number of cells. Cells 

 spherical, fusiform, ovoid, pyrif orm, or ellipsoid ; with two cilia of equal 

 length at the anterior end. Chloroplast typically cup-shaped, posterior, 

 and with one pyrenoid. Cells uninucleate, generally with two con- 

 tractile vacuoles at the base of the cilia; with or without an eyespot 

 which, when present, lies in the anterior portion of the cell. 



Asexual reproduction by division of cell contents to form 2-16 bicili- 

 ate zoospores. 



Sexual reproduction isogamous, by the division of cell contents into 

 8-64 zoogametes that fuse in pairs to form smooth-walled or sculptured 

 zygotes. 



KEY TO THE SPECIES. 



Cells spherical. 



Anterior end without a beak C. GLOBOSA 



Anterior end with a pronounced beak C. EPIPHYTICA 



Cells ovoid. 



Chloroplast cup-shaped and basal C. SNOwn 



Chloroplast laminate, lateral, or basal C. DINOBRTONI 



CHLAMYDOMONAS GLOBOSA Snow. PI. 16, Fig. 8. 

 Bull. U. S. Fish Comm. 22: 389, pi. 1, figs. HP-HP. 1903. 



Cells spherical or slightly ellipsoid, without an anterior beak. Chloro- 

 plast cup-shaped, occupying the greater portion of the cell, with one 

 pyrenoid at the posterior end. Eyespot present, small, generally in the 

 middle third of the cell. Cilia slightly longer than the cell and with a 



