620 MOSQUITOES OF ^s^ORTH AMERICA 



6. Comb of scales in an irregular double row; tube with several dorsal tufts 



trichurus Dyar (p. 761) 

 Comb of long scales in a straight row; pecten of tube running to apex 



walkeri Theobald (p. 851) 

 Comb a patch of scales; tube with one pair of hair-tufts 7 



7. Pecten of the air-tube with detached teeth; abdominal hairs normal 



C epactius Dyar & Knab (p. 643) 

 \atropalpus Coquillett (p. 640) 

 Pecten evenly spaced; short abdominal hairs stellate, husckii Coquillett (p. 861) 



8. Pecten of the air-tube with detached teeth outwardly 9 



Pecten of the air-tube with evenly spaced teeth 16 



9. Air-tube four times as long as wide; comb a patch of scales three rows deep. . 10 

 Air-tube three times as long as wide or less 12 



10. Lateral abdominal hairs double fletcheri Coquillett (p. 678) 



Lateral abdominal hairs single 11 



11. Both pairs of dorsal head-hairs multiple fiiscus Osten Sacken (p. 731) 



Both pairs double ahfitchii Felt (p. 690) 



Lower pair single sansoni Dyar & Knab (p. 687) 



12. Antennae large, enlarged basally; tuft rather beyond the middle 



aurifer Coquillett (p. 768) 

 Antennae moderate only, tuft before the middle 13 



13. Dorsal head-hairs simple; comb of only a few large scales 



spencerii Theobald (p. 725) 

 Head-hairs double or multiple; comb-scales smaller and more numerous. ... 14 



14. Lateral abdominal hairs double on third to fifth segments 



sylvestris Theobald (p. 696) 

 Lateral abdominal hairs single beyond second segment 15 



15. Air-tube stout, pecten usually with two detached teeth, tuft before outer 



third; comb of few scales impiger Walker (p. 757) 



Tube more slender, pecten usually with three detached teeth, tuft at outer 



fourth; comb a patch of many scales fuscus Osten Sacken (p. 731) 



16. Comb-scales few, in a single or irregularly single row 17 



Comb-scales more numerous to many in a patch 26 



17. Anal segment ringed by the plate 18 



Anal segment not ringed, at least a small space along the ventral line 21 



18. Anal processes moderate, normal 19 



Anal processes very long with a stout central trachea 



dupreei Coquillett (p. 780) 



19. Anal segment with dorsal tufts and hairs 20 



Anal segment dorsally with two pairs of hairs only 



abserratus Felt & Young (p. 753) 



20. Comb of about six scales atlanticus Dyar & Knab (p. 801) 



Comb of ten or more scales serraUis Theobald (p. 796) 



21. Air-tube over 4X1; comb of many scales in a long row 



aureostriata Grabham (p. 858) 

 Air-tube 3 X 1 or less; comb of few scales 22 



22. Air-tube pecten dense, strongly spiral viediovittata Coquillett (p. 823) 



Air-tube pecten normal, nearly straight 23 



23. Comb-scales smooth, sharply pointed 24 



Comb-scales smooth or nearly so, bluntly rounded 25 



Comb-scales sole-shaped calopus Meigen (p. 836) 



24. Comb-scales separate; body glabrous H. equinus Theobald (p. 873) 



Comb-scales joined; body densely pilose H. capricornii Lutz (p. 877) 



25. Short abdominal hairs normal; anal plate smooth triseriatus Say (p. 765) 



Short abdominal hairs stellate; anal plate spined behind 



albonotata Coquillett (p. 855) 



26. Anal segment ringed by the plate 27 



Anal segment not ringed by the plate 35 



27. Scales of comb thorn-shaped or with distinct central spine 28 



Scales of comb evenly fringed, without central spine 33 



28. Comb-scales about 14, thorn-shaped, without fringe auroides Felt (p. 751) 



Comb-scales more numerous, with distinct central spine and lateral spinules. 29 



29. Lateral hairs on abdominal segments 3 to 5 double 30 



Lateral hairs on these segments single 31 



30. Air-tube less than 2% X 1; anal gills short, bud-like 



sollicitans Walker (p. 660) 

 Air-tube over 3X1; anal gills normal mitchellw Dyar (p. 666) 



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