338 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
I make the following extract from a report prepared at Dr. Hayden’s request by 
Mr. Campbell Carrington and published in the re^iort cited above, pp. 97-98. 
A curious fact * * * is couuected with these fish, namely, that among their intestines, and 
even interlaced in their solid flesh, are found intestinal worms varying in size, length, and thickness, 
the largest measuring about 6 inches in length. On cutting one of these Trout open, the first thing that 
attracts your attention are small oleaginous looking spots clinging to the intestines', which, on being 
pressed between the fingers, break and change into one of these worms, small, it is true, but never- 
theless perfect in its formation. From five or six up to forty or fifty will be found in a trout, varying, 
as I said before, in size, the larger ones being found in the solid flesh, through which they work their 
•way, and which in a very short while becomes almost putrid. Their number can generally be esti- 
mated from the aiipearance of the fish itself; if many, the trout is extremely poor in flesh, the color 
changes from the healthy gray to a dull pale, it swims lazily near the top of the water, losing all its 
shyness and fear of man; it becomes almost savage in its appetite, biting voraciously at anything 
thrown into the water, and its flesh becomes soft and yielding. If, on the other hand, there are few or 
none, the flesh of the fish is plump and solid, and he is quick and sprigbtly in all his motions. I 
noticed that it was almost invariably the case when a trout had several soars on the outside o^the body 
that it was free from these worms, and therefore took it for granted that the worms finally worked 
their way through the body, and the flesh on healing up leaves the scars on the outside ; the trout in a 
short time becomes plump and healthy again. 
Mr. Carringtou, after proposiug a theory to account for these worms, further 
states that “while all the fish above the upper falls are more or less affected by 
them, below aud even between the upper and lower falls such a thing as a wormy 
trout is never heard of.” 
Allusion to the wormy trout of Yellowstone Lake is made by F. H. Bradly in 
Hayden’s Eeport on Montana, Idaho, Wyoming, and Utah, 1872, p. 234. 
Capt. William A. Jones, in his Eeport on Northwestern Y yoming, including Yel- 
lowstone National Park, 1873, p. 22, speaks of this parasite as follows: 
We find, as others before us, that the trout of the lake (Yellowstone) are perfectly splendid in size 
and condition, hut are full of parasitic intestinal worms, which leave the intestines and enter the flesh. 
The specimens submitted to Dr. Leidy for examination were in a bad state of 
preservation. It was therefore difficult to make out details of structure. Upon com- 
paring my specimens with Dr. Leidy’s figures I was at first led to think that there 
might be two distinct species of the genus Dibothrium represented by the parasites of 
these trout, but I now think that the difference must be due to the macerated condi- 
tion of the material upon which Dr. Leidy based the original description. 
I make the following extracts from Dr. Leidy’s notice of this worm, which was 
published in Hayden’s Eeport on Montana and Adjacent Territory, 1871, pp. 381-382 : 
Among the specimens submitted to me were several of the worms inclosed in oval sacs imbedded 
in fragments of flesh. The sacs having remained unopened preserved the contained parasite from the 
general decomposition of the others, so as to enable me to ascertain its character. It belongs to the 
geuus Bothriocephalus, or rather to that section of it now named Dibothrium. Two species have long 
been known as parasites of the salmon and other members of the same genus of fishes in Europe, but 
the tape-worm of the Yellowstone trout appears to be a difi'ereut one. 
Two of the best-preserved specimens of the tape-worm measure .5 inches in length by a line in 
width at the broadest part. The head, almost a fourth of a line in diameter, is obcordate, as repre- 
sented in the magnified figures subjoined. The two hothria or suckers are thick and discoidal, placed 
hack to back, obcordate in outline, and directed with their broad and slightly depressed surface toward 
the margin or narrower diameter of the body. The body is flat, thick, with rounded margins, and is 
narrowly annulated. The annulations appear to be due to muscular bands, aud number about ten to 
the line. If other segments exist, independent of these annulations, as a character of the worm, the 
