Diseases of Fishin the Adirondacks II 
of very cool water and yet the perch in the surrounding ponds are 
badly parasitized. It is certain that these spring-fed ponds harbor 
parasitized perch even where the water is coolest. 
The food of the perch was examined with some care on each trip 
in the several ponds kept under observation during the summer. The 
first dozen fish examined gave as much variation as was found during 
the entire summer. Snails, caddis-fly larvae encased in tubes of sand 
or sticks, an occasional dragon-fly larva and small minnows constituted 
the range of food for the perch as observed in these ponds. One 
perch was taken that had recently eaten a minnow (probably Pime- 
phales notatus) which had a Clinostomum inbedded in the tail. The 
minnow was partially digested and one Clinostomum lay exposed and 
dead in the flesh of the minnow. It is well known that the pickerel 
feed upon the perch, and finally after much endeavor one was taken 
which had recently fed on a parasitized perch and in which the condi- 
tions were ideal for determining the fate of Clinostomum in the 
stomach of the pickerel. It was found on the mucous membrane of 
the stomach and was dead. In these two observations both parasites had 
the characteristic dull whitish appearance of the dead worm. The 
digestive tracts of several pickerel were examined critically and in no 
instance were any living Clinostoma found. It would seem from these 
two observations that the Clinostoma encysted in the flesh of fish when 
eaten by the perch or pickerel are quickly killed in the stomach and 
eventually digested. 
The genus of flatworms known as Clinostomum has been familiar 
to American Trematode experts since Joseph Leidy in 1856 first 
noticed a cyst on the gills of the sunfish. Osborne, ’11, summarizes 
the several contributions that have been made to the distribution and 
occurrence of Clinostomum marginatum in North America. The 
several observers* report the finding of this parasite in the intestine 
of the pike Esox, upon the gills or encysted in the muscles of the 
perch Perca flavescens, in two species of bass, Roccus lineatus and 
*Linton, E. R., 1910. The diagnosis of a case of parasitism in 
the brook trout. Proc. Seventh Internat. Zool. Congress, Boston, 1907. 
* Osborne, H. L., t91r. On the distribution and mode of occurrence 
of Clinostomum marginatum, a trematode parasite in fishes, frogs and 
birds. Biol. Bul. Vol. 20. 
* Cort, W. W., 1913. Notes on the Trematode genus Clinostomum. 
Trans. Am. Micr. Soc. Vol. 22. 
