WISCONSIN PHTTOPLANKTON 81 



KEY TO THE FAMILIES. 



Cells epiphytic CHLOBOSACCACEAE 



Cells free-floating. 



Length of cells several times the diameter OPHIOCYTIACEAE 



Length of cells less than twice the diameter. 



Cells irregularly distributed throughout an ovoid 



gelatinous envelope CHLOBOBOTRYDACEAE 



Cells arranged about a common center within an 



irregular gelatinous envelope BOTBYOCOCCACEAE 



Family CHLOROSACCACEAE. 



Cells epiphytic, solitary, gregarious, or embedded in an amorphous 

 gelatinous matrix. Chromatophores one to several, parietal, of a yel- 

 lowish-green color, with oil not starch the assimilation product. 



Asexual reproduction by a formation of zoospores that presumably 

 have two cilia of unequal length. 



Sexual reproduction by the fusion of isogamous zoogametes. 



PERONIELLA Gobi 1887. 



Cells epiphytic upon other algae, solitary or gregarious. Shape of 

 mature cells globular to ovoid, of young cells pyriform to ovoid. Cells 

 attached to substratum by a delicate hyaline stipe that is usually some- 

 what longer than the cell. Chromatophores one to two, pale yellowish- 

 green, without pyrenoids or starch and with oil as the assimilation 

 product. 



Asexual reproduction by the division of cell contents into 2-4-8 uni- 

 ciliate (?) zoospores that are liberated by a lateral rupture of mother 

 cell wall. Zoospores swarming a short time and then coming to rest 

 upon substratum and developing into vegetative cells. 



PERONIELLA PLANCTONICA G. M. Smith. PI. 15, Fig. 4. 

 Bull. Torr. Bot. Cl. 43: 476, pi. 25, fig. 15. 1916. 



Cells broadly ovoid to pyriform, with a long, delicate, hyaline stipe 

 that is without a disc or other enlargement at the base. Chromato- 

 phores usually single, rarely two, pale yellowish-green, without pyre- 

 noids or starch. (Euplanktont). 



Cells (without stipe) 6-9.5 /, long; (with stipe) 15-18 /t. Stipe 8-10 ^ 

 long, 1.2 p, broad. 



In gelatinous envelope of Spkaerozosma filaments. 



Devils (1) (rr). 

 6 



