190 Journal New York Entomological Society, [vol. xiv. 



17. Pecten r of air tube running about one-third; anal segment wider than 



long punctor 



Pecten of air tube running about one-half; anal segment longer than 

 wide ' atlanticui 



18. Comb scales smooth or nearly so, bluntly rounded 19 



Comb scales sole-shaped with trifid apex 20 



Comb scales long, pointed, thorn-shaped philosophicus 



19. Short abdominal hairs normal; anal plate smooth triseriatus 



Short abdominal hairs stellate; anal plate spined behind. ... albonotata 



20. Air tube pecten small, in a straight row calopus 



Air tube pecten long, strongly spiral mediovittata 



21. Anal segment ringed by the plate 22 



Anal segment not ringed by the plate 3 1 



22. Air tube over twice as long as wide, its pecten of 19-22 teeth 23 



Air tube twice as long as wide or less, pecten of 12-14 teeth 26 



23. Scales of comb with central spine shorter than the body of the scale; 



pecten of the air tube of equal teeth 24 



Scales of comb with central spine as long as body of scale; pecten of 

 air tube longer outwardly 25 



24. Air tube two-and-a-half times as long as wide; comb scales moderate, 



thorn-shaped sollicitans 



Air tube 3 x 1; comb scales long thorn-shaped mitchellce 



25. Air tube pecten to beyond middle of tube: comb of 21 scales in nearly 



three rows trivittatus 



Pecten not to middle of tube; comb of 17 scales in two imperfect rows 



aur aides 



26. Scales of comb feathered on the sides with central thorn; pecten reaching 



half the length of tube: body glabrous infirmatus 



Scales of comb evenly spinulated without centra! thorn 27 



27. Body glabrous inconspicuus 



Body pilose 28 



28. Pecten to four-fifths of tube; tuft almost apical hemisurus 



Pecten scarcely over half of tube; tuft normal 29 



29. Lateral hairs single on third to fifth abdominal segments cuplocamus 



Lateral hairs double or in threes on these segments 30 



30. Anal segment short with narrow chitinous ring damnosus 



Anal segment moderate with broad ring habantcus 



31. Tube long, 4x1; trachea; narrow, angled jitclui 



Tube three times as long as wide or less 32 



32. Anal plate small, not covering more than half of the segment; anal gills 



very large, sac-like, spotted van' palpus 



Anal plate covering more than half the segment; anal gills moderate .... 33 



33. Comb scales tapered, a single median spine stouter or longer, differentiated 



from the rest 34 



Comb scales bluntly ended, the median spine resembling the others. ... 40 



34. Both median head tufts multiple 35 



Lower head tuft single or double (rarely three) 37 



