10 THE WANDERINGS OF ANIMALS [CH. 



Urchins, which led him to establish four realms of 

 the oceans, justified also by climatic and other physical 

 conditions. 



In an anniversary address to the Geological 

 Society, 1870, Huxley pleaded for various former 

 land connexions and considerable marine changes. 



Whilst English, American, German and French 

 scientists were thus hard at work at reconstructing 

 the history of the world it having become thoroughly 

 understood that the key to the present distribution of 

 any group of animals or plants lies in the past the 

 year 1876 marks a new period with the appearance 

 of A. R. Wallace's great work. These volumes, sup- 

 plemented by the fascinating Island Life, have 

 indeed popularised the study of geographical dis- 

 tribution, and there is now an ever widening circle 

 of enthusiasts far beyond the professional brother- 

 hood. His works have become the classics of our 

 science and they will remain so, but they have also 

 had some influence not altogether advantageous. 



He accepted Sclater's six regions with slight modi- 

 fications and divided each into four subregions, but 

 did not follow Huxley's courageous changes and 

 logical subordinations. Holding the view of the per- 

 manence of the oceans and therefore comparatively 

 small changes of land, he accounts for the coloni- 

 sation of outlying islands (especially his ' oceanic 

 islands') by further elaborating the views of Lyell 



