FOOD AND PARASITES OF SOME FRESH-WATER FISHES. 521 
Fish in || Fish in 
Food. which | Food. which 
found. || found. 
Insect larve ..-. se 39) pelant remains =.= s-: saseeee cesses Te 2 
Gard anidsrereeee.  etee ceo 2 45|\ePlamictom << .e22 3s co- cee neces cscesclsencs 16 
Snails, mostly Phys Se GR EMG OW Sao c gece see cane seceetemaae | 2 
(CHES HIEIS\ 3 < que CORES Eeeee een Sone QO) || HISDY Spa wiml-c2-accse soo snacmaea ae cease | g: 
The 39 perch in which insect larvee were found contained, as far as 
we could determine, phryganid larvee in but 1 and dragon-fly larvee in 
9 fish. Thirty-six of the entire number contained but a single kind of 
food, 15 had 2 kinds, 2 had 3 kinds, and 3 were found with 4 kinds of 
food. In nearly every perch in which more than one kind of food was 
present, insect larvee were found. Forbes (4) gives the food of the 
perch he examined and we note a great similarity to what we recorded. 
He found that a number of fish were eaten by the perch he examined 
from Lake Michigan, due, no doubt, to the smaller amount of insects, 
erustacea, and mollusks present in the large lake. : 
The following table will show the kinds of parasites found and the 
abundance and distribution of each kind in their hosts: 
Gall 
Stomach. pace Toten. blad- 
aan der. 
2. : ene ar : | Jee 
PRS rer iO GCS eee ere ee eae eee arava eps ane iainlafalaielasiseeiete tc 10 29 | Ul | 2 
(ORGICIIET Se Geese co odesoe gee oseees Gund aes PacpSEEeuausecaaceencr Lal syeeee eres PB BB eesce 
INCA NOYES a dae dein cep ee aBenO ne Oe See ORES aDoo DOnr RO OReCBADo eae 5 Dal We menses 
PAlcaminacephalln pan se eee eem ese Meet J he Soe ge easak 7 3 | 1A Saas 
| 
Clinostomum heterostomum on gills, 8; eopepod (Lrgasilus) on gills, 9; cestode and nematode liver 
cysts, 39; cysts in mesentery, 6; cysts in wall of stomach, 2. 
The trematodes were nearly all )/stomum nodulosum, which was by 
far the most prevalent parasite. The number of times trematodes 
were found in the gall-bladder was far greater than given in the table, 
many fish having been examined without being recorded. In late 
July and early August perch were found with a small immature 
fluke present in considerable numbers in the gail-bladder, more than 
half the specimens examined being so infected. It occurred to us that 
this might be the young form of D. noduloswm, which is probable, 
although, the specimens in the gall bladder being immature, it was 
impossible to make a direct comparison. In more than half of the 
perch examined the liver contained cysts; many of these we opened 
and found that they inclosed either a young cestode or a young nema- 
tode. The nematode cysts were generally smaller and firmer than 
those containing the cestodes, but it was impossible, unless every one 
was opened, to be sure of the contents. There was undoubtedly but 
a single species each of cestode and nematode forming the cysts. 
The 16 perch caught during February through the ice were taken 
much farther from shore than any of the others we examined. Four- 
teen of these had fed exclusively upon plankton. They contained as 
large a proportion of encysted parasites as any of the other perch, 
