I40 REPORT OF NEW JERSEY STATE MUSEUM. 



a year with so little change of color that they can hardly be 

 distinguished from fresh specimens, save for their greater 

 opacity." Length 6 mm. 



Remarks. — This species occurs occasionally on Bsox reticu- 

 latus, the common pickerel of New Jersey waters. I have no 

 New Jersey specimens, however, but include the species for the 

 above reason. My description, given above, is drawn up from 

 an example I secured May loth, 19 12, which dropped, or was 

 rubbed off of a roach, Abramis crysoleucas, which I angled in 

 the Pocomoke River near Willards, in Maryland. This host 

 was of the usual size, about six inches long, and infested with 

 numerous parasitic protozoa. The species has not been secured, 

 so far as I can find, on any other host than Esox reticulatus, 

 prior to this time. Dr. Wilson observes "they have not been 

 looked for in a single pond where they have not been found, 

 and in all probability they infest this fish more or less through- 

 out its habitat." The variegated- and brilliant coloration will 

 distinguish this species from all the others of the genus. 



Wilson states that by actual experiment they have been found 

 capable of living on red-fin shiners, breams, etc., for a long time. 

 He says the parasites were placed directly upon the red fins. 

 They attached themselves at once, seeming to prefer the neigh- 

 borhood of the dorsal and ventral fins, and, so far as watched, 

 made no attempt to crawl under the opercle. 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. Remiaining thus 

 upon the external surface where they could be easily watched, it 

 was seen that the individual parasites changed about consider- 

 ably from one fish to another. One of the red fins proved par- 

 ticularly attractive, and often had nearly all the parasites (fifteen 

 in number) on his body. He was no larger than some of the 

 others, but very plump and vigorous. Although the red fins 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 the Arguli, which were placed free in the aquarium 

 for that purpose. Finally one of the parasites fairly rublDed 



