332 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



mackerel, about 2 iuches long, was one day placed in an aquarium with 

 a medusa, wbose swimming-bell measured about 5 inches, in diameter. 

 The next morning Eisig found that the medusa had lost all the points 

 of its tentacles, for the fish had eaten them. Soon after that he had an 

 opportunity to observe another fish in the act of nibbling at the me- 

 dusa, so that there can be no doubt as to these facts. But that the fish 

 did not choose this food, because there was lack of other suitable food, 

 is indicated by the following : A larger fish, about 6 inches long, which 

 lor some time had been in a basin where there were no medusae, took 

 no food at all, and finally became so weak that it looked as if it was 

 going to die. But after a medusa had been placed in the basin the 

 languid fish became very lively, constantly swam round the medusa, 

 and soon began to nibble at it. 



Two circumstances are remarkable in this observation. In the first 

 place these fish can sport about unharmed among the tentacles of sea- 

 nettles which possess the power of stinging severely, while many other 

 fish, and frequently such as are larger than those referred to, are found 

 dead, hanging to the points of the tentacles. In the second place these 

 fish are able to eat a substance which acts like poison on most other 

 fish, or which is at least refused by them. Although the observations 

 in most of the cases referred to above seem to indicate that the fish 

 derives the principal advantage from this companionship, there is nev- 

 ertheless something mysterious about this relation. It is very evident 

 that it is an advantage to the fish to live in a place shunned by its ene- 

 mies, and where it has free access to suitable food. But on the other 

 hand it is very remarkable, and agrees but little with what is known of 

 similar relations between other animals, that this companionship should 

 be maintained unless it is an advantage to both parties. The most 

 plausible explanation seems to be that the protection enjoyed by the 

 fish is compensated by the fact that the medusa every now and then 

 seizes and kills a fish. But what does the medusa gain by having a 

 fish living inside its body, as has been observed in the Indian Ocean 1 



I 15.— NEW ENOIiAND FISHERIES IN JULY, 1885. 



By W. A. WILCOX. 



If it was not for an unusually light demand and extremely low prices 

 for all kinds of fish, the New England fisheries would be in a prosperous 

 condition; as it is, although fish are plentiful, and vessels arrive from 

 short trips with good fares, prices are so low that few vessels are more 

 than paying expenses. 



During the past mouth squid and herring have been abundant in the 

 weirs along the Massachusetts coast, supplying the ground fishermen 

 with plenty of good fresh bait. 



