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 



CMronomus 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- 



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

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

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



— Labium not as above IT 



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



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



Genus ineertus A (p. 532) . 



— ^landibles 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, which 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 broad tooth without indications of indentations though 

 not smooth apically 20 



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



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



— Sides of labium sloping Init 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) . . 



Diamesa waltlii (p. 410) . 



