xxii PREFACE. 



The conclusions at which we arrive are that while the fauna and flora 

 of Palestine are decidedly Palsearctic in type, and belonging to the 

 Mediterranean section of that type, there are traces of a boreal fauna in 

 the north, and a large infusion of Ethiopian types in the Jordan valley : 

 and that these exceptions can be satisfactorily explained only by a 

 reference to the geological history of the country, which shows that the 

 glacial period, though not extending in its intensity so far south, has left 

 traces not yet wholly obliterated ; while the preceding period of warmth 

 has left yet larger proofs of its former northern extension in the unique 

 tropical outlier of the Dead Sea basin, which is analogous both in its 

 origin, and in the present isolation of its various assemblages of life, to 

 the boreal outliers of our mountain tops and our deep sea bottoms ; the 

 concave depression in the one case being the complement of the convex 

 elevation in the other. 



College, Durham, 



December \lfh, 1S83. 



