HYDROPSYCHIDEH. PSYCHOMYIDE. 
the larve of aquatic insects, such as mayfly nymphs and the larve 
of Chironomids. 
In eating the insects the larve do not chew their victims, but 
grasp them with their fore legs and thrust them bodily into their 
alimentary cavity. 
DESCRIPTION OF THE LARVaA.—The head is small. On the 
inner margin of the left mandible there is a tuft of bristles. The 
labrum is entirely chitinized. 
All three thoracic segments bear dorsal chitinous plates. The 
prosternal horn is lacking. Branched gills are present on the meso- 
and meta-thorax. 
The abdomen bears branched external gills and retractile rectal 
gills. Spacing-humps and the lateral fringe are lacking. There 
is no chitinous shield on the dorsal surface of the ninth segment, 
but the ventral surfaces of the eighth and ninth segments bear 
chitinous plates. Each proleg is armed with a tuft of long bristles 
slightly above the claw. 
FAMILY PSYCHOMYID. 
The family includes only four genera and about thirty-five 
species. Of these all are confined to Europe, except a half-dozen 
species belonging to two genera, which occur in North America. 
The life histories of none of the North American species have 
been published. 
DESCRIPTION OF THE Larva:.—Head, prothorax, and the last 
abdominal segment smaller than the rest of the body. Head com- 
pressed. Mandibles asymmetrical, the left with two teeth on the 
inner margin, and with a thick brush of hairs in the groove; the 
right mandibles lacks teeth on the inner margin, and lacks a brush 
in the groove. On the thorax the pronotum alone bears a chi- 
tinous plate. The prosternal horn is lacking. 
The Europearr species of the family make no portable cases, 
but live on stones in long, loosely-spun galleries of silk and sand 
grains. They are found mostly in swift water, but also inhabit 
ponds and lakes. 
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