Fifteen species belonging to seven genera are described, with pictorial and dichotomous keys to identification and notes on their distribution in other regions. All occur on or adjoining the shore, or on seaweeds cast ashore. Seven species are always attached to algae or Amphibolis. The predominant species are: near Sydney, Eulaeospira convexis, Pileolaria pseudomilitaris, Janua formosa and J. pseudocorrugata;near Adelaide (on cast weed), Metalaeospira tenuis and Janua steueri; and on Kangaroo Island, Romanchella quadricostalis, Janua pagenstecheri and (less commonly found) Protolaeospira canina and Protolaeospira triflabellis. Janua lamellosa, J. fenestrata and J. trifurcata seem scarcer, whilst only one specimen was found of the remarkable Amplaria spiculosa, which is now known from New Zealand.
Of these species, most of the opercular incubators are widespread in warm seas, but those which incubate in their tubes may be endemic and mostly belong to genera centred in the Southern Hemisphere, round which they may perhaps have been distributed by drifting kelp.