THE CRUSTACEA OF NEW JERSEY. 141 



against a red fin's nose in swimming about, and the latter, unable 

 to resist such a call, opened his mouth and apparently swallowed 

 the Argulus. But it was only apparently, for in a moment or two 

 the Argulus was forcibly ejected uninjured, and no further 

 attempt was ever made to swallow one. 



Wilson further states that while the parasite is only known 

 fiom the pickerel (Bsox retiadatus) , it may likely be found upon 

 other fish at the breeding-season. According to him, not more 

 than two or three specimens are found upon a single fish, and 

 these always in the gill-cavity. Often it is necessary to examine 

 fifteen to twenty fish before finding a single parasite, so that they 

 could be easily overlooked, and a good summer catch of fish may 

 not reveal their presence. For this reason Avinter is the best time 

 to secure them upon fish caught through the ice, and as they 

 remain alive for some time after the fish is dead, an entire day's 

 catch can be looked over. In this manner as many as thirty have 

 been obtained in a single afternoon from three adjacent ponds. 

 Thus far they have not been sought in a single locality without 

 success. When kept in aquaria they are lively, moving about and 

 changing from one fish to another more often than other species. 

 The long plumose setae upon the swimming-legs make powerful 

 oars, and enable them to dart about with great rapidity. One of 

 their favorite movements is to leave the side of the aquarium 

 and, turning back downAVard, scuttle swiftly along the under 

 side of the surface film of the water after the manner of the very 

 much slower aquatic snails. 



Order GIRRIPEDIA. 



The Barnacles. 



Size often considerable. Body imperfectly segmented. Either 

 fixed or parasitic during adult life. Sexes united and sperms 

 motile. 



Though the barnacles include many genera and species but few 

 have been recorded from New Jersey. Likely many will be 

 added with future collections. In drawing up the present account 

 I have followed the descriptions given by Darwin in his celebrated 



