171 



Finally, it may be observed that since the whole of Britain 

 was severely glaciated, the return of the land-fauna must have 

 taken place from the Continent, across lands now covered 

 by the North Sea and the English Channel. Doubtless 

 the fluctuations of climate in post-glacial times affected the 

 terrestrial animals to a greater or less degree, but a consideration 

 of these changes must be left for a future occasion. 



Of course, in a short paper like this, only a very imperfect 

 outline can be given of such an extensive subject. Many 

 interesting aspects of the fauna have had to be omitted, and 

 others just briefly touched- upon. We have, however, been 

 enabled to perceive clearly the largeness and variety of the 

 fauna of Cleveland, and the interesting problems it presents. 

 Above all we have learned that it is far from being fixed, 

 and that like all other existences it conforms to the great 

 law of evolution. 



