Pearse—The Parasites of Lake Fishes, 
165 
Bothriocephalus cuspidatus Cooper 
This tapeworm was found in the intestine of the perch. 
Glochidia 
Probably all the glochidia observed were Lampsilis luteola 
Lamark, which is the most abundant species in the lakes along 
the Yahara River. 
Piscicolaria sp. ? 
This leech was usually attached about the bases of the fins. 
Unknown cysts 
Very often cysts were encountered among the viscera that could 
not be identified. 
The four lakes along the Yahara River decrease in size and 
depth downstream and come thus in the following order: Men- 
dota, Monana, Waubesa, Kegonsa (Table 3). Lake Wingra is 
small, shallow, and is connected with Lake Monona through a nar¬ 
row, swampy stream. In general the perch increase in size down¬ 
stream, but average smaller in Lake Wingra than in Lake Men- 
dota (Pearse and Achtenberg, 1920). 
The results from the five Yahara lakes may properly be com¬ 
pared for the months of July, August, and September, when col¬ 
lections were made in all of them. During that time the total av¬ 
erage parasitism* for each lake was: Mendota, deep 66.7 (60.7); 
Mendota, shallow 120.9 (67.7); Monona 84.8 (18.8); Wingra 38.8 
(38.6); Waubesa 24.9 (16.4); Kegonsa 40.9 (13.4). The figures 
in parenthesis represent the total average infection without the 
averages for Diplostomum cuticola^ which, when it occurs in very 
large numbers on even one fish, may change the total very much. 
The figures in parenthesis are probably better as a basis for com¬ 
parison. In any case it is apparent that a decrease in infection 
is generally correlated with larger size in these lakes. Before the 
writer had studied lakes along other rivers he thought that a 
greater infection might occur in deeper lakes, or in those nearer 
the headwaters of a stream. 
The different kinds of parasites varied greatly in abundance 
in the lakes. Table 1 shows that the perch in the shallow water 
*Average total number of parasites per fish. 
