Observations on the variability of the Tasmanian Unio

Having collected many specimens of the genus Unio inhabiting the northern rivers of Tasmania, during the last seventeen years, more especially those found in various parts of the South Esk Eiver, I have often been much impressed with the extreme variability of form and colour exhibited by different individuals. This is more particularly remarkable if specimens marking different stages of growth are compared with each other. Includes illustrations.