250 DURHAM DIPTERA. 



XXXIII. 450. 



18 (17) (19). Abdomen with reflections, rather indistinct. 



8 mm. (lugubris, Mg.) 



19 (17) (18). Abdomen with only a central stripe ; small 



species. 4-5 mm. 



1956. Hyedotesia umbratica, Mg. 



Belburn, 1 $, May; Bishop Auckland, 1 ?, June, 

 1900; Wearhead, 2 $, June, 1901. 



(Note.— Mydea nigritella has the eyes slightly hairy; a small black 

 species with very dark wings). 



20 (16). Abdomen oblongo-conical. 



21 (22). Hind femora elongated ; abdomen with a central 



stripe. 



1955. Hyedotesia longipes, Ztt. 

 Wynyard, 1 $, June, 1902. 



22 (21). Hind femora of ordinary length ; abdomen without 



marks, immaculate. 



1954. Hyedotesia variabilis, Fin. 

 Harperley, 1 $, June, 1902. 



23 (15). Abdomen partly yellow ; arista only subplumose at 



the base. 



1957. Hyedotesia semicinerea, W. 

 Bedburn, 1 $, June, 1905. 



24 (1). Legs partly pale yellow or orange. 



25 (50). Thorax and abdomen black or grey. 



26 (49). Arista with long hairs. 



27 (35). Abdomen with distinct spots or stripes. 



28 (33) (34). Abdomen with a central row of triangular spots. 



29 (32). Tibiae only testaceous. 



30 (81). Dorsum with four post-sutural bristles. 



(1958. lata, Fin.) 



31 (30). Dorsum with three post-sutural bristles. 



(2005. Spilogaster trigonalis, Mg.) 



32 (29). Legs all pale except the fore femora and the tarsi. 



(2004. Spilogaster fuscata. Fin.) 



33 (28) (34). Abdomen with wide interrupted central stripe. 



(1959. perdita). 



