INTRODUCTION. 
FAMILY CHARACTERS OF TRICHOPTEROUS LARVA. 
Prolegs not fused in median line to form an apparent tenth segment. 
DorSAL SURFACE LENGTH 
FAMILY B ABDOMEN. | OF 9TH ABDOMINAL Tee LABRUM OF 
.: SEGMENT FRONS 
Much wider | Withchitinous | Absent Entirely Normal 
HyYDROPTILIDE than thorax |_ shield chitinized 
; Not much With chitinous Absent Entirely Normal 
RHYACOPHILIDA wider than shield chitinized 
thorax 
x ~*~ Not much Without Present. Entirely Normal 
HyDROPSYCHID& wider than chitinous shield | Branched | chitinized 
thorax 
Not much Without Absent Entirely Normal 
PHILOPTOMALIDA wider than chitinous shield membran- 
thorax ous. 
White. 
Not much Without Absent Entirely Long. 
POLYCENTROPIDH | wider than chitinous shield chitinized | The _ 
thorax epicrania 
barely 
meeting 
behind its 
caudal 
margin 
ae Not much Without Absent Entirely Normal 
PsYCHOMYID& wider than chitinous shield chitinized 
thorax 
is thought that they are used in cutting through the case at the 
time of emerging. The maxillary palpi are well developed and 
have the same number of segments as those of the adults. 
The thoracic segments are formed much like those of the adult. 
The second and third segments have external wing-pads, and all 
three segments possess jointed legs. ‘The legs are much like those 
of the mature insect, but often possess long swimming hairs to 
enable the pupa to reach the surface of the water and a suitable 
place for transformation. 
The abdomen is- formed much like that of the imago, but is 
usually longer and more flexible. Gills and lateral fringe are com- 
mon among the pupe. Usually they are found in the same species 
that possess them as larvee, but this rule does not always hold true. 
The dorsal surface of segment one usually bears a chitinous struc- 
ture that may be paired or single. Its general form, together with 
its ridges and teeth, offers good family and specific characters. 
Other segments of the abdomen bear paired chitinous plates near 
their anterior margins, with armature of stout teeth or hooks di- 
rected forward. Besides these, segment five bears a pair of plates 
on its posterior margin, with teeth directed forward. Rarely simi- 
lar plates are found on the caudal margins of one or two other seg- 
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