Genus: Test elastic, membranous, in a firm cup-shaped outer test (Illustrated Guide, 1985). Species:

50 μm 100 μm 150 μm; x 400

Frenzelina reniformis Penard, 1902: Cup 26-30 μm across, 12-15 high; sac 12-15 μm diam.; test rigid, clear, membranous, hemispherical, a gelatin-filled cup; attached sand granules; pseudostome at end of sac, 3-4 μm, with collar 1 μm high; nucleus spherical, 3 μm, endosome 1.5 μm (Illustrated Guide, 1985).