710 Wisconsin Academy of Sciences , Arts and Letters. 
with rounded protuberances at the outer posterior angles, the 
whole densely hairy with black bristles; two brushes of these 
black bristles extend up on the face. Mandibles long, incurved, 
with a cluster of black bristles near the base on the under sur¬ 
face. The left bears five strong teeth, the right four. ISTo 
lateral line of hairs, but, as in the larva, on each of the segments 
3-7, a pointed protuberance having the appearance of a short 
simple gill-filament projects backward from the posterior edge; 
sometimes one or two smaller ones are present in front of the 
large one. Gills occur in two rows on the ventral part of each 
of the segments 2-7; each is very complex, consisting of one or 
sometimes two stalks, bearing 6-12 branches. 
Case .—The larva protects itself with a large, loose mass of 
vegetable debris and silk fibers, in front of which is erected a 
net for the capture of prey. When time for pupation arrives, 
it surrounds itself with a more firm structure of sand or £ne 
gravel, measuring about 10-13 mm. in length, by 4-6 mm. in 
width. This is closed anteriorly and posteriorly by a sieve- 
membrane. 
Habits and Occurrence. —These larva? are quite plentiful in 
the swift water of the Yahara where it leaves Lake Mendota, a 
stone taken from the swiftest water being thickly covered with 
them and other Hydropsy chid larva*. Indeed, the number may 
be said to vary somewhat as the swif tness of the water. As this 
water is at the temperature of the lake, it is here very well 
demonstrated that it is the swiftness of the stream and not the 
coldness, that determines their presence. One wonders how they 
are able to cling to the smooth stones of their habitat, until, after 
a collecting trip, one observes them climbing up the smooth, 
perpendicular sides of a glass jar. Then they may be seen to 
be spinning industriously as they climb, building thus a net or 
ladder by means of which the ascent is made. Xo doubt this 
method of making a firm foothold as they go, is directly correl¬ 
ated with their habitat. 
Adults were taken with the trap and from the shrubbery in 
Tennv Park in late June and early July. 
(PL LIII, Pig. 7. PL LX, Pigs. 7-19.) 
