344 THE AMEBIC AN NATURALIST [Vol. LII 



wild state does not usually harbor more than a half dozen, 

 and this number does no serious harm to the trout, espe- 

 cially where they are attached to the fins. 



When this pest gets into a hatchery, but little can be 

 done. The infested trout at the Wild Kose Hatchery in 

 Wisconsin were treated with " solutions of copper sul- 

 phate, potassium chlorate, sodium chloride, and mixtures 

 of sodium chloride and potassium chlorate, but these had 

 no effect upon the parasite" (Fasten, 1911-12, p. 17). 

 About the only remedy that is effective is to destroy all 

 of the parasitized trout, which can be done after the 

 spawning season ; for there is no reason to believe that 

 these parasites can be carried from one place to another 

 except in the manner described by Fasten. We do not 

 know how these parasites pass the winter, but in view of 

 the fact that they are not known to eat during their free- 

 swimming period, it is probable that those which live 

 through the winter do so as parasites upon trout. Dur- 

 ing the cold weather the growth changes would not take 

 place as rapidly, so that a given parasite might remain 

 on a trout for five or even six months during the winter. 

 Clinostomum marginatum. 



This is a small Trematode that lives for a part of its 

 life embedded in the muscles of several food and game 

 fish. The popular name of "grubby" is used to describe 

 this condition. So little is known about this parasite that 

 renders thousands of dollars worth of fish unsuitable for 

 food that any new facts are welcome. In this connection, 

 the following field observations are recorded upon this 

 very annoying parasite. In an earlier paper ( Small wood, 

 '14) attention was called to the fact that these worms mav 

 voluntarily leave the body of their host after the host dies. 

 On May 28, 1914, about 50 perch were taken from McCau- 

 ley Pond between Saranac Lake village and Lake Clear 

 Junction. After returning to camp, it was noticed that 

 these perch were "grubby" and they were all left in a 

 pile on the ground. The next morning, I examined the 

 pile of perch and was able to pick up more than 100 flat- 



