FISH ENTOZOA FROM YELLOWSTONE PARK. 561 
larger specimen was brownish red. They are also much like the speci- 
mens mentioned below from the sucker. 
CATOSTOMUS ARDENS. 
But one species of nematod was found in this fish. These were slender 
white worms, found in the intestine of their host, where they were 
associated with Hehinorhynchus globulosus and Monobothrium terebrans. 
They were from 6 to 8 mm. long and about 0.3 mm. in diameter. They 
taper toward each end alike. The body in alcoholic specimens appears 
to be marked with fine longitudinal striz. The lateral lines are promi- 
nent. When treated with glycerin fine transverse strize became visible. 
The lips are not well defined, but are apparently three in number, with 
several minute papilla. The reproductive organs are rudimentary. 
In the absence of distinct characters, it is of necessity impossible to 
refer these larval nematods to established species. 
WASHINGTON AND JEFFERSON COLLEGE, 
Washington, Pa., April 3, 1891. 
H. Mis. 113——36 
