220 THE CANADIAN ENTOMOLOGIST. 



6a. Dorsal surface of head flattened, forming a broad disk, in- 

 closed by a heavy horse-shoe shaped ridge or carina, making 

 a false clypeus. This carina crosses the true clypeus near 

 its apex, setting off a small triangle. (Fig. 10.) Mandibles 

 toothed on whole inner margin; teeth broad and blunt; 

 interspaces broad and deep. (Fig. 13) 



'. Macroneniatince ( Fam . Hydropsychid(p) 



■fib. Dorsal surface of the head flattened, but disk not so sharply 



defined and practically limited to the true clypeus. (Fig. 11.) 



No carina. Mandibles with sharp teeth at apical end. 



Hydropsychince ( Fam . Hydropsychidce) . 



7a. Labrum not wholh^ chitinized; its anterior angles and mem- 

 brane connecting it to the clypeus, forming a flexible lip, 

 bearing numerous bristles. Uusally the anterior margin of 

 the clypeus is asymmetrically curved (Fig. 9) Philopotamidce. 



7b. Labrum wholly chitinized; its anterior angles rounded. 

 Anterior margin of the clypeus never asymetrically curv^ed 

 ' ...'. 8' 



8a. All three thoracic segments chitinized dorsally 



EconomincB (Fam. Polycenfropidce) . 



8b. Only prothorax chitinized dorsally 9. 



9a. Claws of legs long, slender, with but one basal spur. (Fig. 15.) 

 Labial lobes short, not so long as the maxillary palps 

 (except in Phylocentropiis) . Penultimate segment of 

 maxillary palpus very long. (Figs. 16, 17) ...PolyccnlropidcE. 



9b. Claws of legs short; clatv on first leg bears a basal spur and a 

 bristle beside it. (Fig. 14.) Two basal spurs on claws of 

 second and third legs. Labial lobe long, slender, pointed, 

 generally longer than the maxillary palps. Maxillary palps 

 short; segments of equal length. (Fig. 18) 



PsychomyidcE. 



10a. Labrum with a very distinct row of twenty or more heavy 

 bristles traversing its dorsal surface at about one-third the 

 distance from its front margin. (Fig. 19) 



Calamoceratida . 



10b. Labrum without armature as above in 10a. Generally only 

 three pairs of black bristles on its dorsal surfaces and three 

 pairs of yellow spines on its front margin. (Fig. 20) 11. 



