Pearse—The Parasites of Lake Fishes. 
167 
Winter: Dacnitoides; intestinal proteocephalids; unknown vis¬ 
ceral cysts. 
In order to compare other lakes with deep, fertile lakes along 
the Yahara, eleven lakes on the Oconomowoc and Fox Kivers were 
visited during August, 1917. The general characteristics of these 
lakes are given in table 3. Those on the Oconomowoc were deep, 
with sandy and pebbly shores. Those on the Fox (except Green 
Lake, which was much like those on the Oconomowoc River) were 
shallow with swampy shores. 
Table 3 shows that the average infection was about equal on 
the Oconomowoc (15.2) and Fox (14.4) Rivers; the latter perhaps 
having a slight excess because eight parasites showed the highest 
infection average on it—to five on the former. The Yahara lakes 
showed about two-thirds the infection (9.3) of those on the othei 
two rivers, and the infection average of only two parasites ex¬ 
ceeded those of the same parasites in the lakes on the other rivers. 
In table 4 the lakes of each river system are arranged in order, 
with that nearest the headwaters on the left. It will be seen 
that only on the Yahara was infection greater toward the head¬ 
waters. 
During August infection with all trematodes, intestinal pro¬ 
teocephalids, glochidia, and leeches was greater in the Fox River 
lakes; in the Oconomowoc lakes acanthocephalans, Icthyonema 
cysts, proteocephalid cysts, and unknown cysts were most abund¬ 
ant. The Yahara lakes showed the highest infections with acan- 
thocephalan cysts and Bothriocephalus. 
Except for Diplostomum, the trematodes were most abundant in 
the shallow lakes. Acanthocephala occurred in largest numbers in 
the deep, sandy, and rather barren Oconomowoc lakes; but acantho- 
cephalan cysts reached their greatest numbers in the deep, fertile 
Yahara lakes. Dacnitoides was somewhat more abundant in the 
shallow lakes than in the sandy, barren, deep lakes and was absent 
from the deep, fertile lakes. Icthyonema cysts reached their maxi¬ 
mum in Lake Poygan (shallow, swampy) but on the whole were 
slightly more abundant in the deep, sandy, Oconomowoc lakes. 
Intestinal proteocephalids (P. pearsei La Rue) also were prevalent 
in the shallow, swampy lakes, but encysted proteocephalids, mostly 
P. amhloplitis (Leidy), reached their maximum in the sandy, deep 
lakes. Bothriocephalids were most abundant in the deep fertile 
lakes. Glochidia and leeches reached their maxima in the shallow. 
