of the Yellowstone and Firehole Rivers. 168 
one to three pounds each. They are very abundant; but five 
out of six of them were infested with a singular parasitic worm, 
which is found in the abdominal cavity, or interwoven in the 
muscular portions in sacs or cysts, or sometimes in the gills, 
Dr. Leidy has described these worms under the name of Diboth- 
rium cordiceps. It is possible that this diseased condition of the 
fish is caused by the proximity of the hot springs, which are 
abundant all around the shore of the lake and sometimes ex- 
tend far out into the waters. 
We cannot at this time present a full description of a lake 
a 
which would of itself furnish the material for an extended 
time. The two lakes were then connected, although probably 
never completely united, The belt of mountains that separated 
_ them was about four miles in width. have estimated that, 
fall every second or two, and, with each pulsation, throw out a 
small quantity of water. Quite a pretty symmetrical funnel- 
