Genus Cucurbitella Penard, 1902
Diagnosis: shell ovoid, with distinct apertural collar; outline regular, body constructed of small to medium, angular mineral grains. Organic cement seldom visible as surface structure. Collar with 3-12 lobes, composed of small mineral grains. Internal aperture a diaphragm with a circular or lobed opening on a level with main body wall. Nucleus vesicular. some species with zoochlorellae.
Two Dutch species:
Diaphragm circular: Cucurbitella mespiliformis
Diaphragm three lobed: Cucurbitella vlasinensis