Composed of two Australian subfamilies.
Subfamily Anisopinae
Composed of three Australian genera
Genus Anisops
Genus Anisops
Subfamily Notonectinae
Composed of three Australian genera
Genus Enithares
. 
Composed of three Australian genera
Genus Enithares
Pending ID – Notonectidae
#1. Mid March 2016
Denison Beach
Flew in and landed on a wet glass table that presumably looked like a pond!
. 
#2. Late November 2013
Strathblane
References
Landsbury, I. 1968. The Enithares (Hemiptera-Heteroptera: Notonectidae) of the Oriental region. Pacific Insects 10: 353-442.
Landsbury, I. 1969. The genus Anisops in Australia (Hemiptera-Heteroptera, Notonectidae). Journal of Natural History 3: 433-458.
Landsbury, I. and Lake, P. S. 2002. Tasmanian aquatic & semi-aquatic hemipterans. Cooperative Research Centre for Freshwater Ecology Identification and Ecology Guide No. 40.