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SCIENCE 



[N. S. Vol. XXXVI. No. 919 



bridge across Behriug Strait. Unlike many 

 students, however, he does not think that these 

 are sufficient. He contends that there must 

 have been an early Tertiary trans-Atlantic 

 bridge from southern Europe to a hypothetical 

 " western land " lying just west of the present 

 American continents. This land bridge, ac- 

 cording to Dr. ScharfF, included the Antilles 

 and parts of Central America, and was, by 

 means of the " western land," first connected 

 with both North and South America, then sep- 

 arated from North America, and subsequently 

 reunited with North America and separated 

 from southern South America. By such an 

 hypothesis one can explain the European ele- 

 ments in southwestern North America and the 

 Chilean region. 



The " western land " was. Dr. Seharff be- 

 lieves, part of a great are " which stretched 

 mainly northward, communicating from time 

 to time with Central America and the Antilles, 

 and also with Mexico and western California, 

 and then eventually bending across to eastern 

 Asia in a great loop and thus joining New 

 Guinea, Australia and New Zealand." This 

 bridge is made to account, among other things, 

 for the evidently continental fauna of the 

 Galapagos Islands, the relationships between 

 the living and extinct faunas of western North 

 America and southern South America, and for 

 the Asiatic elements in these faunas. 



As has been intimated, Dr. Seharff believes 

 in a former union of the Antilles with each 

 other and with the trans-Atlantic land bridge 

 and the " western land." He also thinks that 

 the Bermudas and the end of the Florida pen- 

 insula (then an island) were also connected 

 with this land mass. He further postulates a 

 direct connection between Chile and New 

 Zealand, but not by way of an Antarctic con- 

 tinent, and is willing to grant slender bridges 

 between southern South America and South 

 Africa and Madagascar. Although he does 

 not dwell upon these southern bridges, he sug- 

 gests that incentives to migration may have 

 been found in changes in climate due to 

 changes in the direction of ocean currents, so 

 that Simroth's pendulation theory need not be 

 relied upon. 



The author's treatment of the Ice Age in 

 North America will undoubtedly come in for 

 a large share of criticism, for his views are 

 quite different from those now almost univer- 

 sally accepted in this country. Very briefly, 

 it may be said that he denies the existence of 

 continental ice-sheets in the Pleistocene, al- 

 though admitting that this was an age of 

 extensive glaciation, and believes that the 

 climate at that time was temperate and even 

 warmer than at present. The large bodies of 

 water forming the Pleistocene great lakes he 

 attributes to a marine invasion. He does not 

 believe that there was a general southward 

 migration of northern forms in the Pleisto- 

 cene, or that the southeastern states served as 

 " biotic preserves " during the Ice Age, but 

 thinks that the fauna in the drift area was in 

 part destroyed and in part persisted in favor- 

 able localities. He emphatically denies that 

 the evidence is sufficient to warrant the theory 

 that zones of northern animals and plants 

 were spread out beyond the margin of the 

 drift area in a manner comparable to the 

 present distribution in the far north. 



The author himself scarcely ventures the 

 hope that his views on the physical conditions 

 during the Ice Age will be readily accepted. 

 A growing number of zoogeographers in this 

 country will, however, be quite willing to 

 agree with him that current geological opin- 

 ions are permitted to dominate biological 

 thought to a far greater extent than the facts 

 of distribution warrant. We should have 

 more evidence of Pleistocene distribution and 

 not try to erect elaborate theories principally 

 upon geological evidence. It may be pointed 

 out that, granting the ice-sheets, there is still 

 no reason to believe that the margins of these 

 were not covered for miles back with soil and 

 vegetation, as Russel found to be true of the 

 Malaspina glacier, in which case no zonal 

 arrangement would prevail comparable to con- 

 ditions in the Arctic regions at the present 

 time. 



A conviction expressed by Dr. ScharfF that 

 will have adherents is that southwestern North 

 America is and has been in the past a very 

 important center of dispersal, as some previous 



