In the southern hemisphere our knowledge is not nearly so detailed. The presence of marine Middle-Tertiary beds with temperate mollusca in Graham Land and of plant-bearing beds in Seymour Island point to a smaller Antarctic continent and very much warmer conditions at this time in the South as well as in the North Polar regions. For the close of the Tertiary, however, we have strong grounds in the distribution of animals and plants for assuming that the Antarctic continent was greatly increased in size, with promontories uniting it to Australia on the one hand and to South America on the other. New Zealand was largely increased in area, and South Africa probably extended further polewards. The sub-antarctic islands attained a much greater area. Conditions were ripe for the Ice Age in the southern as well as the northern hemisphere. BIBLIOGRAPHY Kerner von Marilaun, F. “Synthese der morphogenen Winterklimate Europas zur Tertiärzeit.” Wien, _SitzBer. K. Akad. Wiss_, 122, 1913, pp. 233-98. Osborn, H. F. “The age of mammals in Europe, Asia and North America.” 8vo. New York, 1910. Nathorst, A. G. “On the fossil floras of the Arctic regions as evidence of geological climates.” London, _Bot. J._ 2, 1913, pp. 197-202; and Washington, _Report Smithsonian Inst._, 1911. Dall, W. H. “On climatic conditions at Nome, Alaska, during the Pliocene.” _Amer. J. Sci._, ser. 4, Vol. 23, 1907, p. 457. Nansen, F. “The bathymetrical features of the North Polar seas, with a discussion of the continental shelves and previous oscillations of the shore-line.” _Norwegian N. Polar Exped._, 1893-96. _Scientific Results_, Vol. 4. Spencer, J. W. “Reconstruction of the Antillean continent.” _Bull. Amer. Geol. Soc._, 6, 1895, pp. 103-40. Wilckens, D. “Die Mollusken der antarktischen Tertiärformation.” _Wiss. Ergebn. der Schwed. Sudpolar Exped._, 1901-3, Bd. 3, 1911. Hedley, C. “The palæographical relations of Antarctica.” London, _Proc. Linnæan Soc._, 124, 1911-2, p. 80. CHAPTER IV THE GREAT ICE AGE