76 WISCONSIN PHYTOPLANKTON 



Division HYDRURINEAE. 



Cells free-floating or sessile, usually in palmella-like colonies and 

 motile only at the time of reproduction; rarely solitary, generally in 

 gelatinous colonies of microscopic to macroscopic size that have a 

 definite to indefinite shape. Colony capable of growth in all parts or 

 with growing region restricted to apex. Gelatinous sheath of cells hya- 

 line, homogeneous or lamellated. Cells ovoid to spherical, with one or 

 two golden-brown parietal chromatophores and with or without a 

 definite wall. 



Reproduction by pyramidate, spherical, or ovoid zoospores with one 

 or two cilia. 



The members of this division are the connection between the normally 

 motile and the highly differentiated sessile Phaeophyceae. 



Order PHAEO CAPS ALES. 



Cells generally organized into free-floating, spherical, ellipsoid, or 

 elongate colonies. Growth of colony taking place in all parts and not 

 restricted to the apical region. Cells variously shaped and with one or 

 two golden-brown chromatophores. 



Eeproduction, aside from vegetative cell division, by the formation 

 of spherical to ovoid zoospores. 



The order contains the single family of the Phaeocapsaceae and only 

 one member of the family, Phaeococcus, is found in the local flora. 



PHAEOCOCCUS Borzi 1892. 



Cells in spherical, ovoid, or irregularly shaped free-floating colonies 

 enclosed by a copious, hyaline, homogeneous or slightly lamellated, 

 gelatinous envelope. Cells ellipsoid to sub-spherical or spherical. Cell 

 number a multiple of two in young colonies, indefinite in older colonies. 

 Cells containing one or more golden-brown chromatophores, sometimes 

 with a red pigment spot. 



Eeproduction by vegetative cell division or direct metamorphosis of 

 cell contents into biciliate ovoid to pyriform zoospores. 



PHAEOCOCCUS PLANCTONICUS W. & G. S. West. PI. 14, Fig. 5. 

 Trans. Roy. Soc. Edinb. 41: 496, pi. 6, figs. 15-16. 1905. 



Cells spherical to sub-spherical, generally distributed in small clumps 

 within a copious, hyaline, homogeneous or radially fibrillar, gelatinous 

 envelope. Number of cells in colony generally 16-64. Cells contain- 



