LIMNOPHILIDZ. 
setee which are curved, but not hooked, at their tips. On the sec- 
ond and third pairs of legs the swimming hairs are well developed. 
The lateral fringe is thick and black; the projections of the last 
segment are much as in L. indivisus (figure 64). The dorsal sur- 
face of the first abdominal segment and the chitinous plates (the 
latter subject to variation in the number of teeth) are shown (left 
side only) in figure 58. 
THE Case.—Length, 20—25 mm.; the breadth varies greatly 
according to the material used in construction. The young larve, 
before they leave the grass on the stream’s edge, make a case of the 
cross-stick type common in this genus. When, as the time for 
pupation draws near, they migrate away from the grassy area, 
their cases take on an entirely different appearance, being con- 
structed of shells, or small chunks of bark, or seeds, from the bot- 
tom. In the meadow area at Michigan Hollow the building ma- 
terial used, after their migration from the shore line, consisted 
almost entirely of the shells of water snails—Planorbis and Sphe- 
rium, for the most part—and of oval seeds. Figure 56 shows a 
case from this area. Higher up in the same stream, where the 
waters are overhung with thickets, the larve use chunks of bark 
in the construction of their cases (figure 52). Different combina- 
_tions of these materials are frequently found, and sometimes cases 
are encountered in which the front part is made of shells or 
chunks, while the hind part retains the cross-stick construction 
used in its previous environment. 
LIMNOPHILUS INDIVISUS. 
Hasitat.—Upland pools or ponds which are rich in decaying 
vegetation and are subject to desiccation during the middle or lat- 
ter part of summer. 
In waters which it inhabits this species is found in extraordi- 
nary numbers, its cases almost covering the bottom of the pond 
during the late larval period. 
Hasits.—During the period when water covers their habitat 
the larve can be found clumsily drawing their bulky cases over the 
bottom of the pond or climbing over the vegetation. Their activ- 
ity, apparently, does not cease during the winter months. 
Early in May, close examination of a pond where the larve 
had been found in great abundance, covering the bottom with an 
47 
