io8 TROPIC DAYS 



to be found on the shore of this bay have been enumera- 

 ted. In a work of general character a complete commen- 

 tar}' on any particular branch of natural science would 

 be out of place, nor is it competent for one who has 

 but a trifling knowledge of a special subject to deal with 

 it in an enlightening manner. It would be highly 

 interesting to ascertain by study and observation why 

 the denizens of so many parts of the ocean meet in 

 communit}- in such a narrow space, though it may not 

 be very difficult to present a fairly satisfactory theory 

 for the continuous presence of many species by reference 

 to existi g features and prevalent conditions. Within 

 the area of the bay the water varies in depth from a 

 few feet to four fathoms, the rise and fall of the tide 

 being about two fathoms. The fringing coral reef 

 represents all stages of development and deca}^ — live 

 growth on the outer edge, ever encroaching on the deeper 

 water, and comprising many varieties; dying masses 

 on the shore-side, and a considerable extent of dead and 

 denuded relics lying in mud. There are also weed}'- 

 patches, bare sand-banks of limited extent, uncovered 

 at low water, and muddy depressions both in the deep 

 and shallow portions and clean sand. Strong currents 

 race past the sand-spit and across the bay, carrying, no 

 doubt, continual supplies of spat from elsewhere to 

 settle in quiet places. No one who has lived on the 

 margin of the tropic sea can be astounded at its prolific 

 life, though it may be a matter of unceasing wonder that 

 along a beach not more than four hundred yards in 

 extent should be found shells representative of species 

 existing in nearly all the warm waters of the world. 



And there arc other isles with other beaches. One 

 ma}'' present a narrow strip of soft sand, cringing and 

 squeaking under foot, almost entirely composed of 

 finely ground coral and shells, among which polished 



