Late Middle Cambrian trilobites from Trial Ridge, southwestern Tasmania

The first Middle Cambrian trilobites to be described from southwestern Tasmania come from two localities within siltstone in the Trial Ridge area on the HUNTLEY 1:50 000 sheet. Sixteen trilobite taxa are described. The 11 agnostoid species include one new species, Hypagnostus trali. Lisogoragnostus is recorded for the first time in Tasmania. The faunas of both localities are of a very similar late Middle Cambrian age, probably high in the Lejopyge laevigata Zone on the northern Australian biostratigraphic scale. One fauna is dominated by complete specimens of Goniagnostus nathorsti but has very few polymeroids. In the other fauna, there are no complete agnostoids, G. nathorsti is absent, and the most common trilobite is a member of the Proasaphiscidae, thus suggesting that the former fauna is of deeper water origin than the latter