8. Setae at the anterior end 9 



8. Setae at the posterior end M. producta 



9. Cells elongate-eUipsoid to subcylindric; 25-45/^ long M. alpina 



9. Cells ovoid; 12-18/i long M. tonsurata 



Mallomonas acaroides Perty 1852, p. 171 



PI. 96, Fig. 22 



Cells ovoid, broadly rounded at both poles but somewhat narrowed 

 anteriorly; scales ovoid to subcircular, arranged in spiral series; 

 needles as long as or a Httle longer than the cell, mostly directed 

 posteriorly (slightly recurved at the tips); cells (7)-15-(23)ju in 

 diameter, 18-23.4- ( 45 )/x long. 

 Rare; in euplankton. Wis. 



Mallomonas acaroides var. Moskovensis 



( Wexmel) Krieger 1932, p. 293 



PI. 96, Fig. 20 



Cells broadly ovoid, I14 to 2 times as long as wide; scales elliptical, 

 very shghtly overlapping; needles in the anterior region directed 

 forward and outwardly curved, other needles straight and directed 

 posteriorly; cells 12-15jli in diameter, 21-25/1, long. 



Euplankter. Wis. 



Mallomonas alpina Pascher & Ruttner, in 



Pascher & Lemmermann 1913, p. 36 



PI. 96, Fig. 19 



Cells elongate-ellipsoid or oblong, usually with broadly rounded 

 poles; membrane covered with rhomboidal scales, so disposed as 

 to form diagonal (spiral) rows, those near the anterior end of the 

 cell each bearing a long needle, the needles directed forward and 

 outwardly curved; cells 8-12/a in diameter, 25-45/1 long. 



Rare; in the plankton of many lakes, mostly semi-hard water. 

 Mich., Wis. 



Mallomonas apochromatica Conrad 1927, p. 440 

 PI. 97, Fig. 3 



Cells oblong to cylindrical, broadly rounded at both poles; scales 

 longitudinally elliptical and imbricate, arranged in spirally trans- 

 verse series; needles few in number at the posterior end of the cell, 

 straight or shghtly curved; cell (22)-32/t in diameter, 58-92/x long. 



Euplankter. Wis. 



[371] 



