(Haeckel, 1887)
Six main spicules of unequal size, two equatorial about twice as long as four polar ; all six spicules of same form, quadrangular prismatic, pointed at distal pyramidal end. Sheaths conical, two to three times as broad at denticulate distal mouth as at narrow base, sulcate; mantle of cone concavely vaulted. Large sheaths envelop two-thirds or three-fourths of spicules. Diameter of shell: 0.1 to 0.13 mm; length of equatorial spicules: 0.15 to 0.2 mm, of sheaths: 0.1 to 0.15 mm; basal breadth of latter: 0.04 mm, distal breadth: 0.12 mm.