Note on a Trematode from Rainbow Trout . 163 
In hatcheries it can be removed and the fish improved by the use 
of a 5 p.c. salt solution, which affects the worm but not the fish, 
but in a large open water this is impossible. The report from 
America where epidemics occurred was always from hatcheries, 
and never from open waters. One report notes the occurrence of 
this worm from the sucker ( Catostomes teres). 
It is further reported from gills of Roecus americanus , which 
enters fresh water to spawn, so that this parasite may be taken at 
times in that habitat. 
Conclusions. 
1. That this trematode acts mechanically at first by stimulating 
the mucous membrane and causing excessive flow of mucus. 
2. Subsequently the gills become bloodless and so the meta- 
bolism of the fish is affected. 
Literature. 
Cooper, A. R., 1915. — Trematodes from Marine and Fresh-water Fishes. 
Trans. Roy. Soc., Cand. (3), 9, 181-205. 
Luke, M., 1909. — Parasitische Plattwiirmer. 1. Trematodes Siisswasser 
Deutschlands, Heft 17, 217 pp. 
Pratt, H. S., 1900. — Synopsis of North American Invertebrates. The 
Trematodes, Part 1, Am. Nat. Hist., 645-662. 
Ward & Whipple, 1918. — Fresh-water Biology. 
