ON THE SAND-REEF AND MOUNTAIN. 235 



or long chain of individuals with its myriad links, 

 takes little account of any one of these items, as 

 long as the line is continued whether it lives a 

 thousand years or only a few weeks matters little. 

 It has therefore followed that the individual is 

 sacrificed that the species may live, and many 

 plants of the sand-reef have become virtually or 

 actually annuals, in the latter case going through 

 their different stages in one rainy season. 



In the south-west of British Guiana is a large 

 tract of country where the bed-rock is sand-stone, 

 and this resembles the Mourie in many respects. 

 The undulated plains which here break the con- 

 tinuity of the forest for large areas are called 

 eppelings. Above the soft sand-stone comes a 

 surface of hard caking mud, or in some places 

 conglomerate, when unbroken resembling a pave- 

 ment of beaten earth, generally of a ruddy brown 

 colour. This covering extends over hill and valley, 

 as well as over the undulations of the savannahs, 

 and would make them real deserts if the rainfall 

 were not so great. However, alternations of 

 burning sunlight and deluge make great seams in 

 the crust, into which water penetrates, producing 

 the effect of a badly laid pavement of irregular 

 flag stones without cement, here and there piled 

 irregularly and alternating with pools of various 



