NORTH AMERICAN CADDIS-FLY LARVZ. 
able from those of Pycnopsyche scabripennis, figures 92, 94. The 
species has not been observed during the early season to ascertain 
whether it makes the flat-leaf type of case. 
PLATYCENTROPUS MACULIPENNIS. 
Hasirat.—The larve live in spring-fed streams, where the 
water is clear and cold, and where the growth of vegetation is 
sparse or wanting. In limited numbers they are found in parts 
of Bool’s Brook, but in the streams of the McLean Basin, espe- 
cially in Argus Brook and the upper regions of Spherium Stream, 
they are among the most common caddis-worms. 
Hasits.—The larve are bottom dwellers in streams with 
gentle current, and without dense growth of vascular plants. In 
such streams they are evenly distributed, apparently never con- 
gregating in certain areas, as do the larve of many other species. 
Before time for pupation the larve attach their cases to sub- 
merged sticks or roots, or hide in the crevices of bark or wood. 
Foop or Larva.—No studies have been made of the food of 
the larve. 
Pertop oF EMERGING.—Adults appear during the middle of 
July. 
Description oF Larva.—Length, 22 mm.; breadth, 4.5 mm. 
Head.—The ground color is straw-yellow, shaded and spotted 
with brown, as in figure 102; on the under-surface there is an 
area of nearly round spots on the posterior part of each gena, in 
front of the spotted area each gena bears a single elliptical coalesced 
pair of muscle-attachment spots. Each mandible, figure 103, 
bears a line of yellow hairs on the upper margin of the inner side. 
The labrum has the straw-yellow ground color of the head, but 
is margined with brown and has a brown spot near its center. 
Thorax.—The prothorax, figure 102, is light-colored, profusely 
spotted with brown. On the mesothorax the chitinous shield is 
smoky-brown, with numerous dark spots, except an area near each 
outer margin where the smoky appearance is absent; the black 
caudal margin of the shield widens at the corners into a broader 
mark, which has a constriction in the middle. The mesothorax; 
on its dorsal surface, is creased by a well-marked furrow, which 
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