403 



— First lateral tooth shorter than central tooth, or at most subequal 



to it 16 



14. First lateral tooth very distinctly longer than central tooth and dis- 



tinctly broader (PI. XXIX, Fig. 22) ; basal joint of apical section 

 of antenna dark, not longer than next joint (PI. XXX, Fig. 8) 

 Genus incertus C (p. 533) . 



— First lateral tooth but slightly longer than the central one and not 



broader 15 



15. Apical jointed portion of antenna slender, subequal in length to 



basal portion; stout species, with the body rounded in cross-sec- 

 tion, and the segments not clearly defined 



Cliironomus lohiferus (p. 430) . 



— Apical jointed portion of antenna stout, distinctly shorter than the 



basal portion; slender, tapering species, the body segments 

 slightly flattened and well defined Cricotopus varipes. 



16. Central labial tooth and all except the first lateral truncated api- 



cally, first lateral very short, and acute at apex (PI. XXIX, Fig. 

 5) ; mandibles without distinct teeth (PI. XXX, Fig. 3) ; antenna 

 as in Figure 6, Plate XXX Cliironomus sp. B (p. 529). 



— Labium not as above 17 



17. Mandibles with two poorly defined teeth (PI. XXX, Fig. 1), 3 very 



large labial teeth, the others short (PL XXIX, Fig. 15) 



Genus incertus A (p. 532) . 



— Mandibles with well-developed teeth; labium otherwise than 



above 18 



18. Central labial tooth very broad, at least twice as broad as first lat- 



eral tooth, central portion of labium paler than lateral por- 

 tions 19 



— Central labial tooth not twice as broad as first lateral ; or the cen- 



tral portion of labium generally as dark as the lateral portions. 21 



19. Central labial tooth regularly rounded, slightly more than twice as 



broad as second tooth, w^hich is pale and rounded (PI. XXIX, 

 Fig. 21) Ortliocladius sp. B (p. 531) . 



— Central pale portion of labium consisting of a very slightly rounded 



and very Inroad tooth without indications of indentations though 

 not smooth apieally 20 



20. Sides of labium sloping very decidedly backward (PI. XXIX, Fig. 



17) ] Ortliocladius sp. E (p. 532) . 



— Sides of labium sloping but little backward (PI. XXIX, Fig. 13) . . 



Ortliocladius sp. A (p. 531) . 



21. Central tooth of labium very much longer and distinctly broader 



than first lateral, first lateral not shorter than second 22 



— Central tooth of labium not broader than first lateral, first lateral 



sometimes shorter than second 27 



22. Labial teeth very acutely pointed (PI. XXIX, Fig. 3) 



'. Diamcsa ivaltlii (p. 410). 



