Description of Hymenomonas

Coccolithophorids, generally non-motile, but when motile with two, subequal flagella and a non-emergent haptonema (i.e. internal trace) or with a short, bulbous haptonema; both cell types bearing hundreds of monomorphic crown-shaped coccoliths, tremaliths, overlying layers of circular organic scales, sometimes also with small elliptical scales; coastal, brackish and freshwater.