Schewiakoff, 1926
One, two, or four radial spicules longer than others. Cell center black or reddish. Peripheral endoplasm and ectoplasm clear. Ectoplasm with numerous elastic junctions. Myonemes very long, mobile ribbons.
Four genera:
Genus Amphiacon
Genus Heteracon
Genus Stauracon
Genus Phatnacantha