DURHAM DIPTERA. 379 



LVI. 656. 



15 (16). Face and frons all dark; V.4 4 about one and a half 



times V.4 3 (VII. 27). 



2790. Borborus equinus, Fin. 

 Very common on dung. 



16 (15). Face black ; frons pale ; V.4 4 about 2-2J times as 



long as V.4 3 . 

 2791. Borborus nigrifemoratus, Mcq. 

 Bishop Auckland, 1 ?, immature, May, 1900. 



17 (14). V.4 4 four times as long as V.4 3 . 



18 (19). Halteres whitish. 



2787. Borborus longipennis, Hal. 

 Bishop Auckland, 3 $, May, 1900. 



19 (18). Base of the halteres blackish. (2788. vitripennis, Mg.) 



20 (3). Dark grey species. (2789- sordidus, Ztt.) 



657. Sph^rocera, Ltr. 

 Larvae live in horse-dung. 



1 (4). Scutellum not toothed. 



2 (3). Fore tarsi not white ringed ; second abdominal 



segment apparently very large and broad. 

 2793. Sphcerocera subsultans, F. 

 Harperley, 1 $, 8-4-06. 



3 (2). Fore tarsi with the end of the first joint and the entire 



second joint white; the second, third, and fourth 



abdominal segments nearly equal. 



(2794. monilis, Hal.) 



4 (1). Scutellum with small teeth round the edge. 



5 (6). Head and thorax chestnut-brown ; abdomen black. 



(2799. scabricula, Hal.) 



6 (5). Head and thorax black or dark brown. 



7 (10). Coxae black. 



8 (9). Hind femora not thickened. (2796. denticulata, Mg.) 



9 (8). Hind femora thickened. (2797. vaporarium, Hal.) 

 10 (7). Coxae partly or wholly yellow. (2798. pusilla, Fin.) 



