THE BUII.DTXG OF AN ISLAND. 



coil or a spiral, that is to sav. ascending- like a screw; in a few species the 

 extension is started on the circular plan and continued on the straight; some 

 again add the cells in a succession of rings, one outside the other; anil some 

 add them alternatelv from side to side, suggesting the idea of their having 

 been interwoven. 



How do these little creatures live? Some kinds, those with the globular 

 shells, for example, have the shells perforated with a great number of fine 

 holes, through which long gelatinous threads are protruded from the body, 

 and with their aid the animals catch the extremely minute particles of food by 

 which thev are nourished and from which thev obtain the lime for their shells; 

 with their aid, also, thev move about in the seaweeds, among which they live. 

 Most of the kinds, however, are not perforated in this way, but have apertures 

 in the last or latest-formed cell, through which similar threads protrude; the 

 other cells are connected with this one and with each other by a small hole, 

 and this enables all \rarts of the tinv creature tt) remain in living connection. 

 It is the possession of these minute holes through the cell-partitions that gives 

 the whole famil\- its name of Foramixifkra (bearers of small holes). 



Contributors tcj the Sea-sand of the Submarine Santa Cruz. 



We mav now leave the consideration of these shells and push our 

 inquiries a step farther. The foraminiferous shells found in the layers of the 

 limestone rocks, prove for us that these layers have been built up from the 

 sea bottom, but, except in regard to the generally small proportion which they 

 themselves contribute, they do not show us 0/ what the rocks have been 

 built up. 



The comparison which we have just made of the foraminiferous shells 

 found in the rocks with those found in the sand of the great shallow that 

 extends around a large portion of our island (the submarine Santa Cruz, as we 

 have called it) suggests at once, however, a method of procedure; it suggests, 

 namelv, that bv stud\ing the story of the sand now forming along our shores 

 and in our shallows, how it originates and how it may be converted, and some- 

 times actuallv is conxerted, into stone, wc rna\' find the solution of our 

 problem. 



The sand on \\\v banks and in our harbours is often called coral sand, but 

 the name is hardly justifiable, since the corals make but a small contribution 

 .to this sand ; still the corals add considerably to the bulk of the accumulations 

 on the sea bottom and are well worth attention. Small corals arc found in 

 many places, but the larger ones belong mostly to the reefs. These reefs are 

 submarine ridges or narrow banks built up of coral and sand. A glance at the 

 map will show that most of our reefs are not situated along the edge of the 

 great bank of sand, but at some little distance within it. The Long Reef at 

 Christiansted, however, and the reef at Buck Island are both not very far from 

 the bank's edge As already said, the reefs are mainly built up of coral. What 

 is coral ? 



