Haeckel, 1882
Spicules very thin, elastic, gradually expanding toward base, fused into homogeneous mass at center. Soft parts spherical and amoeboid, colorless or brownish. Pseudopodia branching and anastomosing; including numerous unbranched ones with axial threads. Central capsule membrane lacking. Ectoplasmic cortex 2-layered; outer one thick, with strongly developed radial elastic filaments; 6-8 band-shaped myonemes. Spicule length: 0.3-0.36 mm, width: 0.0007-0.001 mm; diameter of basal part: 0.008 mm.