204 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Arc.ella discoides. 



Shell mostly circular, flattened disc-like, usually with height of from 

 V4 to % of the breadth; dome low, evenly convex to rounded or slightly 

 expanded and rounded basal border. Base and mouth as in A. vulgarus. 

 Color of shell yellow to dark brown. Plate XXXIII, figs. 42, 43. 

 Arcella milgaris. 



Shell pale yellow to dark brown; watch-glass shape, curved or poly- 

 hedral. Dome evenly convex or angularly faceted or concavely pitted at 

 the summit and sides. The facets or pits variable in number. Mouth 

 circular, mostly entire, rarely slightly crenulated at the border. Sarcode 

 does not completely fill shell. Pseudopods digitate. Nuclei and vacuoles 

 usually numerous. Common in ooze of almost all standing fresh waters. 

 Lawrence golf links. Arcella vulgaris Ehrbg. Plate XXXIII, figs. 37-40, 

 and 43-47; plate XXXIV, figs. 48-50. 

 Euglypha Duj. 



Shell of round oblique rows of plates whose edges cross to make 

 he.xagonal areas. Shell spherical to pear-shaped. Spines frequently 

 present. Mouth surrounded by regular teeth. Sarcode colorless, usually 

 finely granular in posterior portion, coarsely granulated in anterior por- 

 tion. Pseudopodia fine, anastamosing. 

 Englypha alveolata Duj. 



Shell composed of oval plates overlapping each other and arranged 

 in regular rows, producing the appearance of hexagonal areas. Spines 

 often present. E. alveolata is a common rhizopod, being found almost 

 everywhere in fresh water among algse or in the ooze at bottom of ponds. 

 When the spines are present they are long, slender, and often curved, 

 may vary in number from 4 to 6, and are variable in length. Plate 

 XXXIV; figs. 56, 58. 

 Englypha ciliata. Found in connection with figure 58. 



Shell compressed ovoid. Mouth transversely oval. Fundus and lateral 

 borders mostly fringed with spines which vary in number and size. 

 Plate composing shell mostly elongated hexahedral, closely fitting at the 

 margins. Mouth bordered by from 6 to 14 or more blunt, angular, crenu- 

 lated teeth. Plate XXXIV; fig. 57. 

 Assidina Ehrenberg. 



Shell compressed spherical or oval, neck almost obsolete, terminating 

 in a transversely elliptical mouth with uneven or ragged edges, composed 

 of minute oval or hexagonal plates in alternating rows. Sarcode and 

 pseudopods as in Euglypha. 

 Assulina seminidum Leidy. 



Shell nearly as broad as long, oval in shape, compressed, spineless, 

 plates hexagonal or oval. In color ranges from dark brown to trans- 

 parency, ^lates are arranged in alternating rows and at the oval 

 aperture give a notched appearance to the border. Pseudopods are 

 delicate and transparent, branched but not anastomosing. Ooze at bot- 

 tom of ponds. Plate XXXIV; fig. 59. 

 Trine ma Duj. 



Body enclosed within an elongated chitinous shell. Fundus rounded 

 oval; extremity narrower and obliquity truncate. Mouth circular, sub- 



