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THE AMERICAN NATURALIST [Vol. XLVI 



cussion of this bridge between the old and new worlds. In spite 

 of the fact that there are still a considerable number of natur- 

 alists who adhere to the old dicta regarding the permanence of 

 land forms and ocean basins, there can be but little doubt that 

 the open-minded student will be convinced by what Scharff has 

 to say regarding the absolute necessity of postulating extensive 

 changes in the forms of the continents to account for the present 

 distribution of animals and plants. 



Next follows a discussion of Central America and the West 

 Indies (Chapters X and XI). The fauna of both these regions 

 is carefully analyzed and the very many seeming anomalies of 

 discontinuous distribution are explained, often for the first time, 

 by postulating a series of geographical changes far too elaborate 

 to attempt to summarize in a short review. Suffice it only to 

 say that the treatment of the Lesser Antilles is disappointing 

 and the important part which they have played in joining 

 Antillea (sometimes also spelled Antillia), if perhaps only for 

 a very short time, with that region which is now northeastern 

 South America, is overlooked or receives but scant consideration. 

 The existence of Onycophoran types on many of the Lesser An- 

 tilles should have suggested further investigation. 



The twelfth chapter deals wholly with the origin and relation- 

 ship of the fauna of the Galapagos Islands. These islands are 

 also considered to be the remnant of a former considerable ex- 

 tent of land which for a time was connected with a land mass 

 extending from north to south along what is now the west coast 

 of both Americas, but at some distance out in the Pacific Ocean. 

 This connection of North with South America is certainly nec- 

 essary to explain a host of otherwise inexplicable distributions. 

 Parts of the present territory of Central America are known to 

 have been submerged up to comparatively recent geologic times. 

 Baur's pioneer theories regarding the Galapagos Islands here 

 receive the appreciation which they have always so richly de- 

 served. They are corroborated by evidence recently accumu- 

 lated, all of which is used by Scharff to fine advantage. After 

 some discussion favoring Scharff 's theory, which presumes that 

 there has been an extensive land mass occupying a considerable 

 part of what is now the Pacific Ocean west of the present lan*' 

 areas, the author passes to a discussion of the South American 

 fauna, which fills the rest of the book. (Chapters XIII-XV, 

 pp. 336-435.) In this the views of von Ihering and Ameghino 

 carry special weight, and to this they are certainly fully entitled. 



