52 LINKS WITH THE PAST [CH. 



those of the date-palm and bears chisters of fruits 

 as large as a man's head ; a single fruit is two or 

 three inches long and its hard fibrous shell is charac- 

 terised b}^ four or five longitudinal ribs (Fig. 5, B). 

 The fruits of Nipa, Avhich may be carried a consider- 

 able distance by ocean-currents without losing the 

 power of germination, are constantly found with other 

 vegetable drift on the beaches of tropical islands. The 

 discovery of fruits of Nipa (or Nipadites), hardly 

 distinguishable from those of the existing species, 

 in Tertiary beds in England, Belgium, in the Paris 

 basin, and in Egypt afibrds a striking instance of 

 changes in the gQpgraphical distribution of an ancient 

 plant now restricted to warmer regions. 



While the higher members of the Cretaceous 

 sj^stem, as seen in the chalk clifis and downs, re- 

 present the upraised calcareous accumulations on 

 the floor of a fairly deep and clear sea, the lower 

 members testify to shallower water within reach of 

 river-borne sand and mud. 'During the Chalk 

 period,' as Huxley wrote, 'not one of the present 

 great physical featui'es of the globe was in existence. 

 Our great mountain ranges, Pyrenees, Alps, Hima- 

 layas, Andes, have all been upheaved since the 

 chalk was deposited, and the Cretaceous sea flowed 

 over the sites of Sinai and Ararat ' (29). 



The Wealden strata, at the base of the Cretaceous 

 system, as seen on the Sussex coast, in parts of the 



