12 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
LIGULA CATOSTOMI FROM STOMACH OF A TROUT. 
On February 8, 1890, 1 received from Professor Jordan some fragments of ligulm 
from the stomach of a trout {Salmo niyMss). 
These specimens were collected July 20, 1889, at Twin Lake, Colorado. 
These fragments are in six or seven pieces, but are plainly pieces of the same worm. 
Their combined length is about 18 centimeters, greatest breadth 1 centimeter, and maxi- 
mum thickness millimeters. The ends of the fragments present a frayed appearance, 
the surface is broken, pitted, the cuticle removed in places, and a general look of incipi- 
ent disintegration, from which I infer that the specimen has been taken into the stomach 
of the trout along with its proper intermediate host. It is without doubt identical with 
Ligula catostomi. The shape, transverse strim, and longitudinal furrows, with the 
profound median lateral furrow, all point conclusively to this identification. Neither 
the anterior nor the posterior end remains intact, and I find from superficial examina- 
tion no evidence of any further ap])roach to the adult condition than maintains in the 
specimens from the abdominal cavity of the sucker. 
There can be but little doubt therefore that Sahno mykiss is not the proper host 
of the adult stage of this worm. 
Further examination of the entozoa of the fish, and also of the piscivorous birds 
of the Yellowstone region will doubtless yield the necessary material for completing 
the history of this parasite. 
Dibothrium cordiceps Leidy.* 
[PL XXV, Figs. 2-5, PI. XXVI, Figs. 1-5, PL XXVII, Fig. 5.] 
These lignite of the trout {Salmo mykiss) were found, not free in the abodomiual 
cavity, as was the case in those from the sucker, but were inclosed in the muscular 
walls of the abdomen. The specimens were collected in the Yellowstone liiver, just 
below the lake, October 10, 1889. 
Smaller forms, apparently of the same species, were found encysted among the 
liyloric coeca, in the liver and in the serous covering of the stomach and intestine. 
These are described below. The specimens from the abdominal walls were in cavi- 
ties lined with connective tissue, the cavities being from 1 to 3 centimeters in diameter. 
Two trout sent by Dr. Jordan were examined. Each of these had a worm 
inclosed in the muscular walls of the abdomen. In one the worm was situated about 
centimeters in front of the ventral fin. It lay amid the muscles, but had displaced 
those lying immediately above and below, so that it lay contiguous to the peritoneum 
and was separated from the skin by a thin layer of fatty tissue. In a piece of the 
abdominal wall of another trout, the ligula lay in an elongated and somewhat irregular 
cavity tunneled out of the tissues, in all some 3 centimeters in length. The cavity in 
both cases was lined with connective tissue (plate XXV, fig. 5). 
These specimens are very much crumpled and folded on account of having been 
hardened in alcohol while still confined in the narrow limits of their cysts. It is there- 
fore difficult to obtain good measurements ot them. One of the longest was measured 
after it had been straightened out as well as could be done in its crumpled condition. 
It was 15 centimeters in length. The diameter of the cylindrical anterior end was 
about 1 millimeter near the end, whence it tapers to a blunt iioint. The greatest 
* Hayden’s report of U. S. Geological Survey for 1871, pp. 301-2. 
