The following paper deals with Uca marionis, and extends the known range of several other Australian crustaceans. The former is represented in the Australian Museum collection by several large series of specimens, which afford an opportunity to give a few notes on the variation and characters of the species. For assistance in the formation of the paper I am indebted to Mr. A. R. McCulloch, whose tuition in the past has laid the foundation of my work. Family Ocypodidae UCA, Leach. UCA Marionis, Desmarest.