Twenty-one species are recorded from Australia, including 3 new species and 10 new records. These are described and illustrated, and a key is given for the known Indo-West Pacific species. First pleopods of the males are considered in greater detail than in past works, and a key based on their features is included. The relative breadth of basal antennal joints varies with sizes of specimens, and is of less taxonomic value than had been supposed. For this and other reasons some species have been relegated to the synonymy. The relationship of Thalamita to other genera, and the existence of species groups within the genus, are discussed and brief biogeographical comments are given.