GlaucillaBergh, 1868 is positively recorded for the first time from eastern Australia, together withGlaucurForster, 1777. The former is allocated toG. mrginutaBergh, 1868 and the latter toG. atlanticucForster, 1777.Glaucillahas multiseriate ceratal clusters (uniseriate inGlaucus), an unarmed penis (armed with a chitinous spine inGlaucas) and several anatomical peculiarities. Glaucid nudibranchs feed upon species ofVelella, PhysaliaandPorpita; nematocysts ofPhysaliaare subsequently employed for defence. BothGlaucusandGlaucillaare potentially harmful to man.