12 
Psyche 
[March 
2. Last abdominal segment never with a sclerotized shield 
above; body campodeiform, the head held straight 
forward, forming a continuation of the long axis of 
the body ; abdomen of nine segments, the prolegs dis- 
tinct from one another; no tubercle on first abdom- 
inal segment; no prosternal horn; no lateral line 
fringe ; abdomen depressed, the sutures between the 
segments deeply impressed; gills usually absent; 
rectal gill structures generally present but not 
always everted; larvae not constructing a movable 
case 3 
Last abdominal segment usually with a sclerotized 
shield above — if lacking it, the body eruciform 
(hypognathous) and the larva living in a movable 
case (Leptoceridae) ; gills usually present 10 
3. Labrum soft, whitish, retractile under edge of frons 4 
Labrum wholly sclerotized 5 
4. Mandible with a prominent tooth at middle of medial 
margin; frons with a deep asymmetric emargina- 
tion : Philopotamidse, subfamily Chimarrhinse 
Mandible with no such prominent tooth ; frons scarcely 
emarginate : 
Philopotamidse, subfamily Philopotaminse 
5. Claws of legs long and slender, nearly straight, with 
only one basal spur; penultimate segment of maxil- 
lary palpus very long : 
Psychomyiidse, subfamily Polycentropodinse 
Claws of legs short, stout, curved ; penultimate segment 
of maxillary palpi not especially long 6 
6. Gills absent ; only two bristles on convex side of man- 
dibles 7 
Gills present; numerous bristles on convex outer side 
of mandibles; all three thoracic nota sclerotized .... 8 
7. Only prothorax sclerotized dorsally: 
Psychomyiidse , subfamily Psychomyiinse 
All three thoracic nota sclerotized : 
Psychomyiidse , subfamily Ecnominse 
8. Gula an elongate, rectangular plate separating epi- 
cranial halves completely; all gill filaments in clus- 
