38 



PROTOZOA 



P. morum Bory. (Fig. 49). Colony up to .09 mm. in diameter: 

 cosmopolitan. 



4. EUDORINA Ehrenberg. Colony more or less spherical, composed 



usually of 32 (occasionally of 16 or 64 cells) which are 

 not close together and do not reach the center, and 

 are surrounded by an envelope; asexual reproduction 

 as in Gonium; at certain times sexual colonies appear, 

 the female being like the ordinary colony, the male 

 colony consisting of long, spindle-like cells which be- 

 come free and unite with the female cells forming the 

 zygotes: 2 species. 



E. elegans Ehr. (Fig. 50). Colony about .15 mm. 

 in diameter: cosmopolitan. 



5. PLATYDORINA* Kofoid. Colony flattened, horseshoe-shaped, com- 

 posed of 16 or 32 cells with the flagella on both faces on alternate cells 

 which are alike; asexual reproduction as in Gonium; sexual reproduction 

 not observed: 1 species. 



P. caudata Kofoid (Fig. 51). Colony about .15 mm. long and .13 

 mm. wide ; posterior end of envelope with 3 or 5 tails : Illinois. 



Fig. 49 



Pandorina morum 

 (Conn). 



Fig. 50 Fig. 51 Fig. 52 



Fig 50 Eudorina elegans (Jordan and Kellogg). Fig. 51 Platydorina caudata 



(Kofoid). Fig. 52 Pleodorina illinoisensis (Kofoid). 



6. PLEODORINA Shaw. Colony more or less spherical, composed of 

 16 to 128 cells, certain of which are reproductive and the rest vegeta- 

 tive, the former being twice the size of the latter, and posterior in 

 position; asexual reproduction as in Gonium; sexual reproduction not 

 observed: 2 species; both in America. 



P. calif ornica Shaw. Cells 64 or 128, half of which are vegetative : 

 California. 



P. illinoisensisf Kofoid (Fig. 52). Cells 32, rarely 16 or 64, 4 of 

 which are vegetative, .12 mm. in diameter: Illinois. 



* See "On Platydorina," etc., by C. A. Kofoid, Bull. 111. St. Lab., Vol. 5, 

 p. 419, 1899. 



t See "On Pleodorina Illinoisensis," etc., by C. A. Kofoid, 111. St. Lab., 



Vol. 5, p. 273, 1898. 



