SOUTHEASTERN UNITED STATES AS A CENTER OF 



GEOGRAPHICAL DISTRIBUTION OF 



FLORA AND FAUNA. 



CHAS. C. ADAMS. 

 CONTENTS. 



1. Introduction 115 



2. Geographical Affinities of the Temperate Fauna and Flora of Eastern United 



States 116 



3. Richness, or Abundance and Diversity of Life 117 



4. Endemisra and Relicts in the Fauna 118 



5. Relicts not Showing Asiatic Affinities 121 



6. Two Centers of Dispersal in Southern United States 121 



7. Criteria for the Determination of Centers of Dispersal 122 



8. Outlets or Highways of Dispersal from the Southeast 123 



9. Desirability of Studying the Variations, from the Center of Origin, along the 



Highways of Dispersal 124 



10. Summary and Conclusion 128 



11. References 129 



INTRODUCTION. 



From 'a faunal standpoint, southeastern United States, exclusive 

 of Florida, is very remarkable. The fauna is not only very rich 

 in individuals and species, but also in endemic forms. Some of 

 these are indigenous, while others are evidently fragments of an 

 ancient and formerly widespread fauna. Another fact which in- 

 creases our interest is the general relationship of this fauna to 

 that of the Northeastern United States, both biologically and 

 geographically, since there can be but little doubt that this area, 

 together with the boreal region, contains the most important 

 centers of distribution for Eastern United States since the Glacial 

 Period. Some of these characteristics are likely to escape notice 

 unless we consider the fauna in its entirety, and not as restricted 

 by geographical limits. 



Many of the characteristics of this fauna have long been recog- 

 nized. It has been well established that the temperate fauna and 

 flora of Northern United States were driven south before the ice of 

 the Glacial Period, and that with the retreat of the ice to the 



