31 Linton, Edwin E. 1893 Report of the U.S. Commissioner of Fish and Fisheries for 1889 to 1891 Washington, D.C. Government Printing Office 545-564 animal studies, chub, Dacnitis globosa, Dibothrium cordiceps, Distomum laureatum, Echinorhynchus globosus, fish, parasites, rainbow trout (Oncorhynchus mykiss), suckers, trout (Oncorhynchusnidae), wildlife health This paper makes the third which the author has prepared for the U.S. Fish Commission on entozoa collected in the Yellowstone National Park. The first of these papers contained a report on two species of larval cestodes, Ligula catostomi from the sucker (Catostomus ardens), and Dibothrium cordiceps from the trout (Salmo mykiss), collected by Dr. David S. Jordan in September and October, 1889. The second paper was a special report on the life history of Dibothrium cordiceps, being the result of the author's investigations, in July and August, 1890, into the cause of the excessive parasitism among the trout of Yellowstone Lake. The present paper contains descriptions of other fish entozoa which were obtained incidental to the inquiry into the life history of D. cordiceps.Aside from the trout parasite (D. cordiceps), perhaps the most interesting form encountered was the monbothrium from the sucker; this appears to be an undescribed species, and I have given it the name Monobothrium terebrans, from its habit of boring a pit in the mucous membrane of its host. I have thought it best also to give a brief account of the anatomy of this singular worm. Some additional notes on the ligula of the sucker have been given. These are based on observations made in July, 1890. That part of the report which relates to the nematodes is necessarily imperfect, owing to the fact that, with the exception of the species Dacnitis globosa from the trout, the specimens were all immature and for the most part few in number. The author has prepared this report for the U.S. Fish Commission on entozoa collected in the Yellowstone National Park. This paper contains descriptions of other fish entozoa which were obtained incidental to the inquiry into the life history of D. cordiceps. Found at Yellowstone Research LibraryNatureBib ID: 87538