Apkil 13, 1900.] 



SCIENCE. 



565- 



riers, such as masses of water and of desert 

 sands. In certain cases these regions, such 

 as Africa, appear to have been so large, dis- 

 tinct and isolated as to have become im- 

 portant centers of the radiation of certain 

 orders of mammals, and almost attain the 

 rank of realms, but regions in general ai"e 

 chiefly and permanently distinguished by 

 the adaptive radiation of families of mammals. 



Arctogfea may thus be still divided on 

 the old lines into five or six regions, the 

 Arctic or Circumpolar ; the Ethiopian or 

 African, south of the Sahara ; the Indo- 

 Malayan or Oriental, including southern 

 Asia and the Malayan islands ; the Ma- 

 lagasy, including Madagascar ; the Nearctio 

 and the Falaearetic. There is no question, 

 as suggested by Professor Newton in bis 

 term ' Holarctic,' and by Professor Allen in 

 1892, in his term 'North temperate,' that 

 the North American (Nearctic) and Ear- 

 asiatic (Palaearctic) regions are now so 

 closely similar that they might be united 

 into one. When, however, the zoological 

 or existing characteristics of these regions 

 are put to a paleontological test it is 

 found necessary to separate them, because 

 throughout the Tertiary period North 

 America and Eurasia were so remote that, 

 to a certain extent, they constituted cen- 

 ters, not only of independent family, but to 

 a limited degree of ordinal radiation. At 

 the same time they were unified, both by 

 frequent intermigrations and by a simul- 

 taneous evolution of allied animals. 



We now come to one of the greatest tri- 

 umphs of recent biological investigation, 

 namely, the concurrence of botanical, zoo- 

 logical and paleontological testimony in the 

 reconstruction of a great southern conti- 

 nent to which the name Antarctica has 

 been given. Following Blanford (1890), 

 in 1893 Forbes* made the first strong 

 plea for this continent. The flood of evi- 



*H. 0. Forbes, Geographical JoiirnaJ, 1893. Also 

 Natural Science, 1893, p. 54. 



dence for the Antarctica theory has now 

 become so strong that only a few de- 

 tails can be mentioned : Forbes (1893) and 

 Milne-Edwards from the consideration of 

 the birds; Beddard (1895) from the study 

 of worms and other invertebrates ; Moore 

 (1899) from the study of the flora of South 

 Africa; Spencer (1896) from the study of 

 the fauna of Australia ; Ameghino, Hatcher, 

 and Ortmann from studies and collections 

 of vertebrate and invertebrate fossils in 

 Patagonia not yet fully published ; Moreno 

 (1899) from the discovery of Miolania, an 

 Australian fossil reptile j'ecently found in 

 South America. From these and many 

 other sources has been brought forth the 

 body of testimony which draws us almost 

 irresistibly * to the conclusion that there 

 was an Antarctic continent at various times 

 connecting South America, South Africa, 

 Australia and New Zealand. Such a con- 

 nection strengthens Huxley's conception 

 announced in 1868, that the zoological re- 

 gions were mainljr upon lines of latitude, 

 rather than as suggested by the present 

 configuration of the earth, upon lines of 

 longitude. With the theoretical elevation 

 of this submerged continent (Chart III.) 

 which may be called the ' Antarctic Ee- 

 gion,' so as to connect the southern land 

 masses at various times, all present and 

 past geographical distribution may be the- 

 oretically accounted for. Elevation to the 

 10,000 foot (3040 meter) line still leaves a 

 broad channel south of Africa. Without 

 such elevation we are still met by many in- 

 superable difficulties. 



Among other problems, a land connection 

 between Africa and Soiith America across 

 the South Atlantic enables ns to explain 

 the remarkable distribution of the sirenia, 

 sea-cows, dagongs and manatees, now found 

 exclusively in the tropical belt of Africa 

 and the Americas. (See Sirenia, Chart 



* After discussing the evidence -with great fairness 

 Lydekker (1896) takes a more conservative position. 



