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American Midland Naturalist Monograph No. 3 



vidual scale trifid, with subapical spines about one-third as long as apical spine. 

 Siphon strongly inflated, about four times as long as basal width; pecten of 3 

 to 5 widely spaced teeth on basal fourth of siphon; subventral tuft minute, 

 multiple, inserted laterally beyond middle of siphon. Anal segment longer than 

 wide, completely ringed by dorsal plate; lateral hair small, usually multiple, 

 branched near base; dorsal brush consisting of a long lower caudal hair and a 

 shorter multiple upper caudal tuft on either side; ventral brush extending 

 almost the entire length of the anal segment; gills 4, longer than the segment, 

 each gradually tapering to a sharp point. 



iTOiS 



Fig. 74. Larva of Psorophora ferox (Humboldt). A, Terminal segments. 

 B, C. and D, Pecten teeth. E, Comb scale. F, Head. 



