390 Wisconsin Academy of Sciences^ Arts, and Letters. 
the temperature of the water rises. Its transparency makes it 
difficult to see and it is probable that it has been overlooked 
in some of the collections from the lake^ where it was found in 
late July and August. Like its relatives it travels on slime- 
trailSj but when irritated will go thru a violent flapping motion 
free in the water^—in fact, an actual swimming reflex resem¬ 
bling the vertical wave-motion of some leeches. 
5. Nemathelminthes. (Table 5, p. 474.) 
Gordius aqiiaticus Linne. 
“Pink’’ Nematode. 
During late June large numbers of young Gordii and of some 
other, “pink” Nematode may be found coiled on plants or on 
the bottom of the lake. Most of these occur in the shallower 
parts, but they are also quite frequent at greater depths. Ap¬ 
parently they have just left their intermediate hosts to search 
for others. Many are of course destroyed during this “free” 
period, which lasts not more than two weeks, while others suc¬ 
ceed in finding a second host. 
Especially Chironomus tentans larvae and pupae are found 
to be infested with Gordius, some containing as many as three 
individuals. Other Chironomid species may also be infested 
with them, notably the larger species C. lobiferus, tentans var?, 
and plumosus; I have not found the worms in the smaller species, 
nor in any other lake insects, (they probably occur in Ephe- 
meridae) altho I have repeatedly observed the unsuccessful at¬ 
tempts of Gordius to enter caddis-worms. 
The “pink Nematode” may be a form of Mermis; I have 
found it in Chironomus palliatus, lobiferus, and viridis. No 
mature specimens were obtained. Gordius adults are not un¬ 
common in the lake and especially its tributaries and basins in 
September, 
6. Chaetopoda. (Table 5, p. 474.) 
Only the larger Annelids have been considered individually 
in the numerical counts. Except for Sparganophilus eiseni 
Smith, which is a purely littoral form, the data given cannot 
be considered complete, for they apply only to the littoral area, 
while at least the Lumbriculids are quite general in their dis¬ 
tribution. 
