Further notes on the fresh-water shells of Tasmania (With a description of New Species)

The publication of the Rev. J. E. Tenison-Woods' paper, in enabhng collectors to determine and compare the catalogued fresh water species with those in their immediate neighbourhood, has been most valuable, and has given a healthy impetus to local observation. As the list, however, was only published by the Society but a year ago, it cannot be expected that any considerable addition could have been made to our knowledge in this particular study since that time. Still, as the types for the various species were mainly derived from southern habitats, it is possible that some varieties peculiar to northern Tasmania may have escaped notice, and consequently there may be a difficulty in the exact specific determination of certain of our northern varieties. Indeed, I find, with respect to Physa, Lymnea, and Bithynella, that the difficulties in the way of classification are very great, because of their extreme variability even in the same habitat. This difficulty is, unfortunately, increased where the full range of variability may have escaped the classifier's notice