During the past two or three years several papers of unusual importance, in my opinion, have appeared on the geographic distribution of terrestrial organisms. These include “Climate and evolution,” 2 by W. D. Matthew; “The development of the natural order Myrtacecse,” 3 “The development and distribution of the natural order Luguminosse,” 4 and “The geological history of the Australian flowering plants,” 5 by C. E. Andrews; and “Plants, seeds, and currents in the West Indies and Azores,” by H. B. Guppy.6 These three authors agree in their main thesis, namely, that vertebrates and plants have spread from northern areas radially southward over Africa, South America, southeastern Asia, Malaysia, and Australasia. They all deny direct land connection, at least since Paleozoic or early Mesozoic time, between Africa and South America and between South America and Australia, and they question there ever having been any such bridges. Furthermore, they all agree, explicitly . . .