2-4; cells 5-12/A in diameter, 18-25/i. long including stipe; stipe 

 9-13^ long. 



Found on members of the Volvocales and on diatoms. Mich., Wis. 



Characiopsis spinifer Printz 1914, p. 44 

 PL 94, Figs. 3-5 

 Cells ovoid to elliptic, with an acute tip, practically sessile on a 

 broad attaching disc; chromatophores several disc-shaped bodies; 

 cells 7-9/x in diameter, 22-30;a long. 



On miscellaneous filamentous algae. Wis. 



PERONIELLA Gobi 1887, p. 244 

 An attached ovate, ovoid- or elliptic-pyriform cell with a narrow 

 stipe which may have a basal attaching disc; chromatophores 1 or 2, 

 yellow-green parietal plates. 



Species of this genus have always been found on algae which 

 are inclosed in a gelatinous sheath. The stipe of the epiphyte pene- 

 trates the mucilage to make contact with the cell wall of the host. 



Key to the Species 



Cells spherical, stipe fine and thread-like P. Hijalothecae 



Cells ovoid or ellipsoid, narrowed below to form a 



slender, but not thread-like stipe P- planctonica 



Peromelia Hyalothecae Gobi 1887, p. 244 

 PI. 94, Fig. 6 

 Cells spherical, 15-20/x in diameter, with a very slender hair-like 

 stipe and a basal attaching disc; chromatophores 2 parietal plates. 



Common in acid habitats; attached to the filamentous desmid 

 Hyalotheca. Mich., Wis. 



Peromelia planctonica G. M. Smith 1916, p. 476 



PI. 94, Figs. 7-9 



Cells broadly ovate, ovoid, subglobose, or pyriform-globose, with 



a tapering stipe which has no basal attaching disc; chromatophores 



1 or 2 laminate bodies; cells 6-9.5/x long without the stipe, 15-18/a 



long including the stipe. 



Attached to the filamentous desmid, Sphaerozosma; in Sphagnum 

 bogs and soft water lakes. Wis. 



FAMILY CENTRITRACTACEAE 



The cells in this family are soHtary and uninucleate. In a few 

 species small aggregates of cells are formed, however. The indi- 

 viduals are fusiform, cylindrical, or rectangular in shape, but in the 



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