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Show 776 PROF. BALDWIN SPENCER ON A [NOV. 20, The following papers were read:- 1. A Description of Wynyardia bassiana, a Fossil Marsupial from the Tertiary Beds of Table Cape, Tasmania. By B A L D W I N SPENCER, M.A., F.R.S., C.M.Z.S., Professor of Biology in the University of Melbourne, Director of the National Museum, Melbourne. [Received July 9, 1900.] (Plates XLIX. & L.) For many years the Tasmanian Museum iu Hobart has been in possession of a block of calcareous sandstone, obtained from the " Turritella-zone " iu the Tertiary beds of Table Cape, containing, partly exposed to view, the remains of a marsupial, which in life must evidently have been of tbe size of a large Phalanger, though of stouter and more massive build than any existing one. I have to express my cordial thanks to the Council of the Museum and to the Curator, Mr. Morton, for the opportunity of examining the specimen, the especial interest of which lies in the fact that it is the oldest marsupial yet found in Australia, as the Turritella-zone is regarded, from palaeontological evidence, as belonging to the Eocene deposits 1. Whilst a large number of fossil mammals from Australia have been dealt with by Owen, McCoy, de Vis, Stirling and Zietz, Broome, and others, none of an age earlier than Pleistocene have been hitherto discovered, tbe specimen now described being tbe solitary one as yet found in Australia which dates back as far as the Tertiary period. Pleistocene fossils reveal the existence of highly specialized forms such as Thylacoleo and Diprotodon, associated with representatives of living genera; whilst the Eocene form appears to be in no way highly specialized, but unites within itself structural features which serve to ally it, on the one band, with the most generalized of the Diprotodontia-the Phalangeridae, and on the other hand with the most typical Polyprotodontia-the Dasyuridae. This is exactly what we might expect to find, on the supposition that the present Diprotodont marsupials of Australia have been developed in the Australian region from earlier Polypro-todont forms, and that the more highly specialized Diprotodonts were comparatively late developments. The earliest and, in fact, the only reference to the fossil occurs in Johnston's ' Geology of Tasmania,' where it is briefly described as " the almost perfect skeleton of a species of Halmaturus obtained 1 G. B. Pritchard, "A Revision of the Fossil Fauna of the Table Cape Beds, Tasmania," Proc. R. S. Vict. 1895, p. 74. Professor Tate, however, has recently referred the beds, doubtfully, to the Oligocene : Trans. R. S. South Austr. vol. xxiii. pt. i. p. 107. |