Schewiakoff, 1926
Spicules long, stiff, of equal size (1-2 mm long); edges may be serrated. Bases of spicules resembling grape seeds embedded in contractile matter. Periplasmic cortex with elastic junctions:
One genus: Gigartacon (Amphiacon and Heteracon are sometimes placed in this family).
Five species:
Gigartacon abcisus
Gigartacon bifidus
Gigartacon cordiformis
Gigartacon denticulatus
Gigartacon fragilis
Gigartacon muelleri