DURHAM DIPTERA. 1 67 



XXVIII. 

 Family XXVIIL— SYRPHID^. 



TABLE OF SUBFAMILIES AND GENERA. 



1 (97). Antennae of moderate length, and more or less droop- 



ing (III. 43, 44); or if rather long and horizontal 

 (Paragus) then not on a produced or prominent 

 frons. 



2 (62). X.4. before the middle of O. (discal cell), i.e., V.4 2 



shorter than V.4 3 (V. 21). 



3 (61). 0.2. open. Arista bare, or at most pubescent. 



Sub-Family Syrphin,e. 



4 (11). Face flat or retreating without a central knob. Eyes 



and face always hairy. 



5 (10). Upper mouth-edge not produced. 



6 (7). Third antennal joint elongate. Pipizella, Rnd.(271) 



7 (6). Third antennal joint not elongate. 



8 (9). Male hind trochanters spurred. 



273. Cnemodon, Egg. (1440. vitripennis, Mg.) 



9 (8). Male hind trochanters not spurred. Female frons 



with grey side dust-spots. Pipiza, Fin. (272) 



10 (5). Face flat, but upper mouth-edge produced. 



274. Psilota, Mg. (1441. anthracina, Mg.) 



11 (4). Face knobbed or arched in the centre, or with a 



cone-like snout. In doubtful species the face and 

 eyes are always almost bare. 



12 (13). Face arched, but not hollowed out beneath the 



antennas. Paragus, Ltr. (270) 



13 (12). Face hollowed beneath the antennae, and with a 



central knob, or produced mouth edge. 



14 (21) (22). Dark species without light abdominal spots, and 



either with eye margins (VII. 5) or furrowed 

 female frons. 



15 (16). Cheeks with a long furrow producing distinct eye 



margins (VII. 5). Chilosia, Mg. (278) 



16 (15). Cheeks not so furrowed. Female frons furrowed 



across. 



