NORTH AMERICAN CADDIS-FLY LARVZ. 
oped; it extends from the front margin of the third segment to the 
hind margin of the eighth segment. The distribution of gills is 
diagrammatically shown in figure 107. 
DeEscRIPTION OF THE Pupa.—Length, 10o—11 mm.; breadth, 
2—2.5 mm. The antenne extend back almost to the tip of the 
abdomen. Each side of the upper surface of the labrum bears a 
group of about five long, black, hooked sete. The mandible is 
shown in figure 198. The lateral fringe begins near the hind 
margin of segment five and curves under the hind margin of seg- 
ment eight; it is black in color and is much better developed than 
that of the larva.. The last segment bears a pair of fleshy ap- 
pendages. The chitinous plates of one side of first and third- 
seventh abdominal segments are shown in figure 114. 
DESCRIPTION OF THE CasE.—The case of the larva, when ma- 
ture, is 15—20 mm. long; its diameter is 4 mm. or more at the 
cephalic end, according to the kind of material used in its con- 
struction. In form it is cylindrical and slightly curved. The 
larve, during their active period before pupation, construct their 
cases largely of quartz sand, but usually have a greater or lesser 
number of bark chunks around this inner cylinder. Sometimes, 
however, these bark fragments are almost, or even entirely, lack- 
ing. In preparation for pupation the larve usually remove almost 
all of the plant fragments from their cases. They then congregate 
in numbers on some support, as a submerged stick or root. Be- 
fore pupation takes place the two openings of the case are stopped 
with small grains of sand firmly cemented in place. Apparently 
there is no mesh left open. Figure 113 represents a typical larval 
case of quartz sand and a few fragments of bark. 
GENUS NEOPHYLAX. 
Head.—The head is very long and narrow, held pointing back- 
ward with the under-side against the under-side of the thorax 
when at rest. 
Thorax. —The prothorax is narrow and lacks the “horn.”” On 
the mesothorax the chitinous plates above the coxe extend back 
until they meet the dorsal plates. 
Abdomen.—A transverse elliptical ring marks the under-side 
of segments three, four, and five. 
72 
