WISCONSIN PHYTOPLANKTON 83 



pale yellowish-green, disciform, parietal, and without pyrenoids. (Eu- 

 planktont) . 



Cells 5-6 fji broad, 6-8 ^ long. Diam. colonies 40-200 //,. 



Camp (IT). 



Family BOTRYOCOCCACEAE, 



Cells always in free-floating colonies of definite or indefinite shape. 

 Number of cells in colony generally indefinite, few or many. Colony 

 enclosed by an envelope that may be hyaline or Colored, gelatinous or 

 leathery. Cells usually ovoid, rarely spherical; with 1-2 parietal, 

 laminate to disciform, yellowish-green to nearly grass-green chromato- 

 phores without pyrenoids and with oil as the assimilation product. 



Asexual reproduction by vegetative cell division. Zoospore forma- 

 tion or sexual reproduction unknown. 



BOTRYOCOCCUS Kiitzing 1849. 



Cells in free-floating colonies of indefinite shape. Cells closely ap- 

 posed to one another and enclosed by a gelatinous or tough membrane 

 that is sometimes wrinkled and folded. Colonies generally with cells 

 in several aggregates that are connected by broad or delicate strands 

 of the colonial integument. Cell shape spherical, ovoid, or cuneate. 

 Groups of cells arranged in a single layer around a common center, or 

 irregular in arrangement. Chromatophore single, parietal, laminate 

 to disciform, yellowish-green to nearly grass-green in color and without 

 a pyrenoid. 



Reproduction by vegetative division of cells. 



KEY TO THE SPECIES. 



Cells held together by a thin gelatinous envelope B. SUDETICUS 



Cells held together by an irregular tough membrane. 



Membrane completely enclosing cells B. BBATJNII 



Membrane covering base only of cells B. PBOTUBERANS var. MINOE 



BOTRYOCOCCUS SUDETICUS Lemmermann. PI. 15, Fig. 8. 



Forschungsbr. a. d. Biol. Stat. zu Plon. 4: 111, figs. 6-7. 1896. 



Botryococcus Braunii G. S. West non Kiitzing, Brit. Freshw. Algae 237, figs. 

 306A-106B. 1904; G. M. Smith, Trans. Wis. Acad. Sci., Arts, & Lett. 18 a : 545 

 1916. 



Colonies free-floating ; spherical or irregular ; with cells held in botry- 

 oidal clusters by a hyaline gelatinous envelope and frequently joined 

 to one another by broad or narrow strands of the gelatinous envelope. 

 Cells spherical to subspherical, 16-32 or more in each botryoidal group, 



