NORTH AMERICAN CADDIS-FLY LARVZ. 
the construction of their cases into the rectangular form charac- 
teristic of older larve. Such cases, (figure 40) with their long, 
protruding ends of leaves, appear superficially very different from 
those of mature larve. Careful examination beneath the protrud- 
ing ends, however, will reveal the characteristic ringed or spiraled 
arrangement of the bases of the untrimmed leaves. 
The cases of Phryganea larve might, from description, be con- 
fused with those of Triznodes. In Triznodes the case is much 
smaller and more flexible. Its spiral is more plainly apparent than 
the spiral of Phryganea, and the leaf fragments are much narrower 
—in most examples almost thread-like. 
KEY TO THE SPECIES OF PHRYGANEA. 
A. Frons without dark markings.—P. vestita. 
A.A. Frons with a median mark. 
B. Median mark extending the entire length of the frons. Dorsal 
surface of the prothorax margined in front and behind 
with dark. No conspicuous dark markings on meso- and 
meta-thorax.—P. interrupta. 
B.B. Median dark mark not reaching the hind margin of the 
frons. Prothorax not margined in front and behind with 
dark, but with two converging dark marks. Meso- and 
meta-thorax with two nearly parallel longitudinal dark 
marks.—P. cinerea. 
PHRYGANEA CINEREA. 
Hapsits.—This species is not known to me in life. The speci- 
mens from which the description is made were taken by Dr. C. 
Betten at Old Forge, New York. 
Although none of the larvee were reared, it seems probable that 
they are P. cinerea, for all known species of the genus, which might 
occur in this state, have been reared, except P. cinerea and P. im- 
proba. Improba is a very rare species, represented in collections 
by only a few specimens. Cinerea is more common and was taken 
at Old Forge by Dr. Betten during the season in which he collected 
the larve. 
When collected, August 8th, one larva had spun the sieves 
across the openings of its case, indicating that its growth was com- 
plete and that it would have emerged about one month later. 
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