W. K. BROOKS ON THE GENUS SALPA. 145 



There is practically nothing in the ocean corresponding to the terres- 

 trial herbivora, and nothing like terrestrial vegetation, except the fringe 

 of seaweeds in the shallow water along the coast, and a few floating 

 islands of algae like the Sargasso Sea. 



While these tracts of vegetation are pretty extensive, they are totally 

 inadequate to support the animal life of the ocean, and as the whole 

 animal world is dependent directly or indirectly upon plants, we must 

 ask what takes the place of terrestrial vegetation. 



The Fauna of Mid-ocean. 



There is so much room in the vast spaces of the ocean, and the part 

 which is open to our direct observation is such an inconsiderable part of 

 the whole, that it is only when great multitudes of pelagic animals are 

 gathered together at the surface that the abundance of marine life 

 becomes visible and impressive ; but some faint conception of the bound- 

 less wealth of the ocean may be gained by observing the quickness with 

 which marine animals become crowded at the surface in favorable 

 weather. 



On a cruise of more than two weeks from Cape Hatteras to the 

 Bahama Islands I was surrounded continually, night and day, by a vast 

 army of dark-brown jelly-fishes (Linerges mercutia), whose dark color 

 made them very conspicuous in the clear water. They were not densely 

 crowded, although they were so abundant that nearly every bucketful 

 of water we dipped up contained some of them. We could see them at a 

 distance from the vessel, and at noon, when the sun was overhead, we 

 could look down into the water to a great depth through a well in the 

 middle of the vessel where the centerboard hung, and as far down as the 

 eye could penetrate, fifty or sixty feet at least, we could see the brown 

 spots drifting by like motes in the sunbeam. We cruised through them 

 for more than five hundred miles, and we tacked back and forth over a 

 breadth of almost a hundred miles, and they were everywhere in equal 

 abundance. 



The recent literature of pelagic exploration, which has been sum- 

 marized by Haeckel (Plankton Studien : von Ernst Haeckel, Jena, 1890), 

 is full of references to great accumulations of pelagic animals, from 

 which I have selected those which follow. 



Chiercha says that during a cruise of forty days between Peru and 

 Hawaii the net brought in from the surface and from all depths down to 



