348 DURHAM DIPTERA. 



XLIX. 



8 (6) (7). Abdomen with five distinct segments in both 



sexes; four scutellar bristles. 

 8a (8b). Arista bare ; second terminal segment lengthened. 



618. Mosillus, Ltr. (2658.. subsultans, F.) 

 8b (8a). Arista combed. 



9 (10). Abdomen broad, almost round ; palpi very broad. 



Discomyza, Mg. (596) 



10 (9). Abdomen not remarkably broad, lengthened, elliptical. 



11 (12). Mouth opening large, praelabrum not protruding. 

 11a (lib). Under half of face somewhat protruding; eyes 



hairy ; two costal spines. Atissa, Hal. (603) 



lib (11a). Under half of face with a nose-like knob; eyes 

 bare ; no costal spine. 



613. Ilythea, Hal. (2642. spilota, Hal.) 



12 (11). Mouth opening not large, praelabrum protruding. 



13 (14) (15). Face on the upper half concave in profile, com- 



pressed, and on the lower half protruding knob- 

 like. 599. Athyroglossa, Lw. (2597. glabra, Mg.) 



14 (13) (15). Face keeled on the upper half, flat on the under 



half, or nearly so, and with several side bristles. 



Discocerina, Mcq. (598) 



15 (13) (14). The whole length of the face flatly convex, and 



with only one side bristle. Psilopa, Fin. (597) 



16 (1). Second antennal joint in front with at most a short 



hair-like bristle (VII. 23, 24); the upper side of the 

 mid tibiae always without strong bristles. 



17 (31). Eyes usually hairy; mouth opening small; face only 



moderately arched (VII. 25, 26). 



Sub-Family Hydrellin/e. 



18 (23) (28). Eyes thickly haired. 



19 (20). Arista pubescent ; dorso-central bristles absent or 



weak. 601. Glenanthe, Hal. (2599. ripicola, Hal.) 



20 (19). Arista combed (VII. 23) ; dorso-central bristle 



distinct. 



21 (22). Face arched; arista long combed (VII. 25, 23). 



Hydrellia, Dsv. (60S) 



