154 DUEHAM DIPTERA. 



XXIV. 240. 



11 (10). Inner lamellae ending in a long, compressed, slightly- 



curved thread, which breaks into ciliation at its 

 tip. ( I 3 II « appendiculatum, Ztt.) 



12 (1). Frons glossed with white ; coxae without any black 



bristles ; hind femora with a praeapical bristle. 



13 (14). Fore tibiae with a bristle and a tiny ciliation beneath, 



the bristle being just below the middle and rather 

 turned back ; outer lamellae short. 



(131 2. brevicorne, Curt.) 



14 (13). Fore tibiae almost bare beneath, and at any rate with 



no distinct bristle ; outer lamellae long, hairy, and 

 ciliated at the base. (1308. fissum, Lw.) 



241. Achalcus, Lw. 



1 (2). Grey species. ( I 3 I 5- cmereus, Wlk.). 



2 (1). Orange species. ( I 3 I 6. flavicollis, Mg.) 



242. Medeterus, Fisch. 



1 (6). Legs entirely black or dark. 



2 (3). Mid tibiae with no bristle near the base ; very small 



species, i-i£ mm. (^S. mura/t's,Mg.) 



3 (2). Mid tibiae with a bristle near the base. 



4 (5). V.5 4 longer than X.5. Halteres with the knob 



darkened. Small species, not more than 2 mm. 



(1319. tristis, Ztt.) 



5 (4). V.5 4 not longer than X.5. Halteres pale. Large 



species, 4-5 mm. (1321^. obscurus, Ztt.) 



6 (1). Legs with at least the knees pale. 



7 (16). Legs yellow, at most the bases of the femora brown. 



8 (9). Scutellum with only two bristles. 



(13 1 7. micaceus, Lw.) 



9 (8). Scutellum with four bristles, as usual. 



10 (11). Mid tibiae with no bristle near the base. 



(13 18. muralis, Mg.) 



11 (10). Mid tibiae with a bristle near the base. 



