SHALLOW-WATER FAUNA OF THE TROPICS. 79 



cannot support a vigorous Coral fauna. Here 

 and there patches of peculiar deep-sea species of 

 Corals occur, but they do not form in such depths 

 anything of the nature of a reef. They are 

 usually isolated specimens, similar to those that are 

 found in deep water on the Norwegian coast and 

 other parts of the world outside the limits of the 

 Tropics ; but these specimens really belong to the 

 deep-sea Fauna, of which we shall learn more in 

 another chapter. 



In many places, however, the water at the 

 base of the outer edge of the reef is not very 

 deep, and may slope away gradually towards 

 the bed of the ocean. The Fauna of such slopes 

 in the Tropics is not characteristically rich, as 

 my own experiences of dredging in such waters 

 have proved. Time after time the dredge that 

 was used in 15 to 20 fathoms off the coast of 

 Talisse, came up with nothing but sand or 

 gravel. Occasionally a Brittle-star or a branch 

 of dead Coral, with a few Zoophytes growing 

 on it, came up ; and in some places a few 

 beautiful Lily-stars or Crinoids relieved the 

 monotony of the investigation. But, on the 

 whole, the animals found in this region were 

 not numerous, nor of a character to excite any 

 particular interest. 



Before bringing this chapter to a close, a brief 

 reference must be made to one of the most re- 

 markable phenomena in the animal kingdom, 

 this is the history of the Palolo worm. On cer- 

 tain parts of the coast of the Samoan islands the 

 Palolo worm appears in great abundance in the 

 early morning hours of one or two days at the 



