254 DUEHAM DIPTEEA. 



XXXIII. 452. 



19a (19b). Abdomen grey; thorax with four distinct black 

 stripes. urbana, Mg. ? (1978) 



19b (19a). Abdomen with dark tesselations ; thorax less dis- 

 tinctly striped. (1982. affinis, Mde.) 



20 (11). Thorax indistinctly striped, or unstriped. 



21 (22). Palpi yellow. 



1984. Mydma impuncta, Fin. 



Bishop Auckland, 6 $ and 6 ?, May-September. 

 Common. 



22 (21). Palpi black. 



1985. Mydcea separata, Mg. 



Harperley, 2 $, June ; Brancepeth, 1 $, June ; Shull, 

 1 $, July, 1902. 



453. Sphecolyma, Perr. 

 1986. Sphecolyma inanis, Fin. 

 Bishop Auckland, 1 ?, July, 1902. 



454. Spilogaster, Mcq. (see also page 256). 



1 (24). Arista plumose. 



2 (13). Legs black, or nearly black in the male. 



3 (4) (10). Thorax black and unstriped ; wings nigrescent. 



1987. Spilogaster nigrinervis, Ztt. 

 Bedburn, 1 $, July, 1897 ; Harperley, 1 ?, June, 1902 ; 

 Bishop Auckland, 4 $, July, 1897. 



4 (3) (10). Thorax with distinct black stripes. 



5 (6). Hind tibiae hairy on the inner side. 



(1990. quadrimaculata, Fin.) 



6 (5). Hind tibiae almost bare on the inner side. 



7 (8) (9). Legs quite black ; three post-sutural bristles. 



(1993. duplaris, Stein) 



8 (7) (9). Knees pale ; four post-sutural bristles. 



1 99 1. Spilogaster duplicata, Mg. 

 Hesleden, 6 $ and 5 ? ; Wearhead, Shull, Shipley, 

 7 $ and 5 $, May-August, 1899-1901. 



