INTRODUCTION. 
Hydroptilide have small, dorsal, chitinous plates on certain seg- 
ments, and a few species in other families have small ventral plates. 
DEscRIPTION OF THE Larva. The Head.—The head is 
heavily chitinized. On the dorsal surface there is a somewhat 
shield-shaped sclerite behind the labrum, which evidently repre- 
sents the clypeus and the frons, fused into one piece. As the 
frons represents the larger part of the sclerite, and because the 
term ‘‘frons” is well established in the nomenclature of other or- 
ders of insects applying to the clypeo-frons (“‘clypeus” is used 
by most writers on Trichoptera), the term frons is used to desig- 
nate the sclerite in the present paper. The shape of the frons 
varies in different Trichopterous larvz, and it usually has a quite 
distinct pattern of color and muscle-attachment marks, as well as 
different distribution of sete, for which reasons it is of great use 
in classification. It is also easily recoverable from the larval exu- 
via of pupal cases, and often forms the most reliable clue to the 
determination of pupz. 
Extending back from the frons to the hind margin of the head 
is the epicranial suture. 
On the ventral surface of the head, behind the mouth parts, 
there is a sclerite, the gula, which varies greatly in size and form. 
Sometimes it extends to the hind margin of the head, completely 
separating the epicrania. At other times it is represented by a 
small, triangular piece, behind which the epicrania are contiguous. 
At such times the gular suture separates the epicrania behind the 
gula. 
The epicrania form the greater part of the head, extending 
from the mouth parts to the caudal margin, and from the frons 
and epicranial suture above to the gula and gular suture beneath. 
The antenne are usually so small that they are easily over- 
looked; occasionally they are almost as long as the mandibles. 
They are located behind the outer angle of the mandibles. 
The eyes are located on the outer edge of the dorsal margin 
of the head, sometimes on prominences. They are usually jet 
black in color and are almost always surrounded by a light-colored 
area. 
The mouth parts are well developed and are formed for biting. 
The mandibles are very heavily chitinized and offer characters 
which would be of great taxonomic value, were it not almost im- 
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