NO. 1302. A MEIiK 'A N PA RA SITIC A R G ULIDJ^- WILSON. 647 



2. A. ver.neoIor Vives upon the pickerel, Lucius reticidatus he i->iumr. 

 Hero again we have a tisli ,so hirgo as to be difficult of transportation 

 alive, and very troublesome to keep in captivity. 



But even the attempt was rendered impossil)l<> in the present experi- 

 ment by the fact that the fish from which the parasites were obtained 

 w ere taken through the ice in January and were all dead when exam- 

 ined. Accordingly the Arguli were transported to the laborator}', 

 and this time some of the redfin shiners {Notropln) which had been 

 used for bait were found to !)(» the most available material for tem- 

 porary hosts. 



In this instance the parasites were placed directly upon the redfins. 

 The}^ attached themselves at once, seeming to prefer the neighbor- 

 hood of the dorsal and ventral fins, and, so far as watched, making no 

 attempt to crawl under the operculum. 



They did not seem to irritate the fish perceptibly, although they 

 could be plainly seen to crowd forward under the scales to pierce the 

 skin. They were kept in this way more than two months, and had 

 almost reached the breeding season when an unfortunate accident 

 killed them all. 



Remaining thus upon the external surface where they could be easily 

 watched, it was seen that the individual parasites changed about con- 

 siderably from one fish to another. 



One of the redfins proved particularly attractive, and often had 

 nearly all the parasites (15 in number) on his own body. 



He was no larger than some of the others, but Avas very plump and 

 vigorous. 



This living upon minnows is in direct confirmation of the observa- 

 tions of Claus (1875) upon the two European forms, A. foliaceus 

 and ^4. coregonl. But the present observations differed markedly 

 from his in one respect; either these redfins were not as yet educated 

 to the use of parasites as food, or they did not relish such a diet. 

 Although they were fiercely hungry when obtained, having been kept 

 without food since they were caught in the fall, no one of them took 

 any notice of some Arguli which were placed free in the aquarium for 

 that purpose. 



Finally one of the parasites fairl}- rubbed against a redfin's nose in 

 swinnning about, and the latter, unable to resist such a call, opened 

 his mouth and apparent^ swallowed the Argulus. But it was only 

 apparently, for in a moment or two the Argulus was forcibl}^ ejected 

 uninjured, and no further attempt was ever made to swallow one. 

 Indeed, none of them disappeared till the final accident whicli killed 

 them all. 



3. ^4. laticauda and ^1. megalops live upon man}- of our common 

 salt-water fish, and some of them were desired for experiments similar 

 to those tried upon the fresh-water forms. 



But it would obviously be impossible to transport them with their 



