134 W. K. BROOKS. 



group of marine animals must consist, in the main, of animals 

 which are able to resist or to escape, and observation shows that 

 this is true. Floating jelly-fishes and siphonophores are often 

 found fastened to the half-digested carcasses of sagittas or hetero- 

 pods or fishes larger than their captors, and they consume enor- 

 mous numbers of copepods, pteropods, young fish, and pelagic 

 larvae of all sorts. So far as we know, all the sea-anemones and 

 coral polyps and alcyonarians and hydroids are carnivorous. Some 

 of the discomedusse, the rhizostomes, feed upon microscopic organ- 

 isms, but this mode of life is exceptional, and some recent observa- 

 tions, as yet unpublished, by Dr. R. P. Bigelow, show that the 

 food of the rhizostomes consists of copepods. 



Except for a few plant-eating fishes and molluscs and worms 

 and echinoderms, all the animals of the ocean fall into two classes, 

 those which subsist on microscopic organisms, and those which 

 prey upon each other and correspond to the rapacious animals of 

 the land. 



There is practically nothing in the ocean corresponding to the 

 terrestrial herbivora, and nothing like terrestrial vegetation, except 

 the fringe of seaweeds in the shallow water along the coast, and a 

 few floating islands of algse 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 inconsider- 

 able part of the whole, that it is only when great multitudes of 

 pelagic animals are gathered together at the surface that the abun- 

 dance of marine life becomes visible and impressive ; but some faint 

 conception of the boundless 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 



