NORTH AMERICAN DIPTERA. 



47 



extremely small, short, minute, triangular, but a little Ioniser than 

 wide, about same shape as the minute processes at base of second 

 joint (see fig. 1). Fans (see figs. 1 and 2) consisting of about sixty 

 scythe-shaped rays each, the microscopically thinly hairy on outer 

 side, sharply widened dorso-ventrally on about their basal one-fourth, 

 and when spread, presenting the appearance about middle of widened 

 portion of a crescentic serrate line extending over the width of fan 



near base. Mmidlbles elongate, 

 rather stout, nearly twice as long as 

 wide, furnished with teeth on inner 

 side at apex; four large teeth on 

 apex, nine or ten teeth behind these 

 gradually decreasing in size, except 

 that the second of these is larger 

 than the first ; a large tooth still 

 behind these, with a small one di- 

 I'ectly beside it ; mandibles furnished 

 with dense brushes of hairs apically, 

 more or less hiding the teeth, and 

 basally, also with a regularly set 

 fringe of hairs extending inward 

 from anterior median portion (see 

 fig. 3). Maxilloi furnished on inner portion with a dense tuft of 

 hairs, on outer with a blunt, subconical, horn-like process (see fif. 4). 



Thoracic proleg 4-jointed, elongate, sub- 

 conical, truncate at end, last joint fur- 

 nished with at least thirty obliquely 

 longitudinal rows of hooks, and prob- 

 ably more; at base of these there is a 

 marginal transverse row of bristles on 

 side toward body (the proleg being 

 flexed forward) extending around lat- 

 erally, but wanting on outer surface. 

 Stigmata (see fig. 5) showing on the dor- 

 sally tuberculiform extremity of body 

 as a wide, transversely corrugated, 

 blackish, more or less irregular circlet, 

 either flattened and slightly indented 

 dorsally, or slightly scalloped ; at base dorsally with an X-shaped 

 crossing, or branching of chitinous rods, the two anterior branches 



Fig. 3. 



Fii,^ 4. 



TKANS. AM. ENT. SOC. XX. 



APRIL, 1893. 



