INTRODUCTORY. 



of nature. There was a period, not very remote, 

 when the botany and zoology of the shore was held 

 to represent the whole of marine life. Then -low 

 water-mark was almost the limit of investigation, 

 and for the majority the absolute limit. Sea-weeds, 

 anemones, shells of molluscs, zoophytes, and stranded 

 sponges, were, apart from fish and Crustacea, the 

 totality of marine life. But now these are almost 

 discarded in favour of the denizens of the depths 

 of the sea. The waves of enthusiasm at different 

 times set in different directions, determined perhaps 

 by some single circumstance, and in that direction 

 which they assume, are probably persistent for a 

 considerable period, until some new impulse is 

 given, and the current is changed. To know some- 

 thing of the most extraordinary of the " Toilers in 

 the Sea," the most expert builders of " ocean homes," 

 we must go beyond the littoral zone, and explore the 

 dark abysses, where the light of the sun and the eye 

 of man has never penetrated. 



All the preliminary facts which it is necessary to 

 call to remembrance here, in reference to the ocean 

 in which our organisms flourish, may be indicated 

 by a short retrospect, for the most part abstracted 

 from Sir Wyville Thomson's " Depths of the Sea." 

 Taking for granted that three-fourths of the surface 

 of the globe is covered by the sea, and until very 

 recent times so little was known of its depths, and so 



