W. K. BROOKS ON THE GENUS SALPA. 143 



among the floating tufts of algae upon its surface, but most of them 

 frequent these places in search of the small animals which live among 

 the plants. All the floating fishes whose home is the floating sargassum ; 

 the file fishes and trigger fishes (Ballistida) ; the trunk fishes (Ostracion) ; 

 the frog fishes (Antennarius) ; and the puffing fishes (Tetradon and 

 Diodon) are carnivorous, living upon the barnacles and molluscs and 

 hydroids which grow upon the sargassum, or upon the Crustacea, young 

 fishes and the floating larvae which seek its shelter. 



In the Chesapeake Bay, the sheepshead (Diplodus probatocephalus) 

 browses among the algae upon the submerged rocks and piles like a 

 marine sheep, but its food is exclusively animal, and I have lain upon 

 the edge of a wharf watching it crush the barnacles and young oysters 

 until the juices of their bodies streamed out of the angles of its mouth 

 and gathered a host of small fishes to snatch the fragments as they 

 drifted away with the tide. 



Many important fishes, like the cod, pasture on the bottom, but their 

 pasturage consists of molluscs and annelids and Crustacea, instead of 

 plants. 



The vast majority of marine fishes are fierce hunters, pursuing and 

 destroying smaller fishes, and often exhibiting an insatiable love of 

 slaughter, as in the case of our own blue-fish and the tropical albacore 

 and barracuda. Others, such as the herring, feed upon smaller fishes 

 and the pelagic pteropods and copepods ; and others, like the shad, upon 

 the minute organisms of the ocean, but all, with few exceptions, are 

 carnivorous. 



In the other great groups of marine animals we find some scaven- 

 gers, some which feed upon micro-organisms, and others which hunt 

 and destroy each other, but there is no group of marine animals which 

 corresponds to the herbivora and rodents and plant-eating birds and 

 insects of the land. The pelagic copepods are, of all the marine Meta- 

 zoa, the ones whose place in the economy of nature is most like that of 

 the terrestrial plant-eaters. They swarm in innumerable multitudes at 

 the surface of the ocean, and also below it down to a depth of a mile or 

 more, and they furnish the chief food for most young fishes, and for 

 great armies of herrings and pteropods and jelly-fishes and siphono- 

 phores, and for most pelagic larvae. 



There are plant-eating molluscs and echinoderms and annelids in 

 the ocean, but not in sufficient numbers to play any conspicuous part 

 in its economy, and the copepods are the only plant-eaters which exist 



